« AnteriorContinuar »
Man glaubt, er sei gefallen.
It is thought he has fallen. They thought I had been sick. It was thought I had never been there.
the frontier. 5. He asserted that it was better to stay at home than to go out. 6. I wish that he may be treated with more kindness. 7. He tells every one that you are a very rich man ; but if you were, you would not be so penurious. 8. Have you Er glaubt, er werte nie wieter glück. He believes he shall never be heard, too, that your friend has fallen from his horse? 9. No, lich werden. happy again.
Sie glaubten, ich sei krank gewesen. Man glaubte, ich wäre nie da ge. wesen.
but I have heard that he has fallen out of the coach. 10. I hope
Man sagt, sie werde bald die Ober. It is said she will soon have the that you will be with your parents in a fortnight. 11. I doubt hand haben.
Rufen, to call.
Ungarn, n. Hungary Verfahren, to act, proceed.
Verstellung, f. dissi
mulation. Verwandt', related. 3war, indeed, it is true.
He asserts that it is true.
It is supposed that we are rich.
are nevertheless welcome. It appears to me that they are Americans.
He appears as though he were not healthy.
I think that he has been sick. They say that he has already been here.
I hope that you will have been fortunate.
He told me you had the teacher's book.
I doubt that the hunter has the
It is supposed that you have much money.
It is known that they have pleasure in this affair.
I heard that he had a large fortune.
The uncle said (narrated) he had had a pleasant journey.
1. Haben Sie auch gehört, ich sei vom Pferte gefallen? 2. Nein, ich hörte, Sie seien aus dem Wagen gefallen. 3. Die Geschichte meltet, taß Tilly, welcher Magreburg im dreißigjährigen Kriege eroberte, sehr barbarisch verfahren sei. 4. Mein Bruder sagte, Sie seien sehr gelobt worten. Die Franzosen behaupten, sie seien die Gebildetsten in der Welt. 6. Ihre Schwester glaubte, Sie wären in der Start gewesen. 7. Die Englänter find der Meinung, fie seien die Herren des Meeres. 8. Dieser Neisende er, jählte, er sei zweimal in Rem gewesen. 9. Er hofft, er werte in acht Tagen in Dresden sein. 10. Sie fürchten, Sie seien zu langsam im Handeln gewesen. 11. Wir glaubten, Sie wären auf dem Lande. 12. Ich glaube, wir wären gestern zu Euch gekommen, wenn das Wetter schöner gewesen wäre. 13. Ich glaubte, er wäre der warnenten Stimme seiner Eltern eingedenk gewesen. 14. Er sagte zwar, er sei krank, aber Viele behaupten, es sei Verstellung von ihm gewesen. 15. Seine Verwandten sagen, sein Glück habe sein Unglück herbeigeführt. 16. Ich hörte mit Berauern, Sie hätten tas Nervenfieber gehabt. 17. Da ich in dem obern Zimmer war, hörte ich Sie nicht rufen. 18. Man erzählt, der Ungar habe bis in den Tod sein Vaterland treu vertheitigt. 19. Ich hörte, dieser junge Franzose werde ein großes Vermögen erben. 20. Ich glaube, daß viele Menschen hier auf Erten ihr Gutes gehabt haben werten.
1. People say these gentlemen have been tipsy, but they are mistaken. 2. They say that residence in Paris is more agree able than in London. 3. We could not believe that this was true. 4. It is universally believed that the enemy has crossed
that he can be so ungrateful. 12. This stranger says that he has been twice to India, and was very sick on his last voyage.
LESSONS IN GEOMETRY.-XII. As the next lesson will put the learner in possession of the last of the problems that we intend to give on the construction of figures contained by three and four straight lines-namely, the
triangle, the square, the rectangle, and the parallelogram—we would recommend him to go carefully over the whole of the present series of problems from the commencement, constructing as many figures as he possibly can, to meet the requirements of the data in each case. And in doing this we advise him to try to construct figures different in form to those which we have given in these pages, as, if he can do this, he may be sure that he has gained a thorough knowledge of the various methods of construction set forth in the different problems.
The problem in practical geometry that was brought before the notice of the student in the last lesson, showing him how to construct a square that shall be equal in superficial area to the sum of two squares described on two given straight lines, has given him the key to the construction of squares, rectangles, and parallelograms, equal in superficial area to the sum or difference of any two or more squares, rectangles, or parallelograms, as the case may be; and it has also shown him that the main principle on which their construction depends, is the relation between the triangle, the figure contained by the least possible number of straight lines (since two straight lines cannot enclose a space, although one curved line can, as in the case of the circle), and all regular figures contained by straight lines-namely, the square, the rectangle, and the parallelogram. It may be as well to repeat that this principle is, that when a square, rectangle, or parallelogram is upon the same base and between the same parallels, the area of the square, rectangle, or parallelogram (as the case may be), is double the area of the triangle.
Now supposing we have a square, rectangle, or parallelogram before us, and we wish to construct a triangle equal in area to either of these figures, what have we to do? Manifestly nothing more than to draw one of the diagonals of the figure in question, produce the base indefinitely in the necessary direction, and, after setting off on it a straight line equal in length to the side of the square, rectangle, or parallelogram, that serves as its base, to join the extremity of the line thus set off with the upper end of the diagonal. This will be evident on an inspection of Fig. 42, where, in the square (rectangle or parallelogram) ABCD, the diagonal A c is drawn; the base C D, on which the square (rectangle or parallelogram) A B C D stands, is produced indefinitely in the direction of F; a straight line, D E, set off along it from the point D, equal to DC; and the straight line E A drawn, joining the points E and A, and completing the triangle AE C, which is equal in superficial area to the square (rectangle or parallelogram) A B C D.
And, conversely, when we wish to draw a rectangle or parallelogram equal to a given triangle, all we have to do is to bisect the base of the triangle, and on either half of the base construct the required rectangle or parallelogram, after drawing through the apex of the triangle a straight line parallel to the base. the case of the rectangle, after bisecting the base of the triangleas, for example, in Fig. 43, where the base of the triangle ABC is bisected in D-and drawing a straight line, PQ, of indefinite length, through the apex A of the triangle A B C parallel to its base BC, a rectangle equal in superficial area to the triangle ABC is formed by drawing the straight lines CE, DF through the extremities C and D of C D, one-half of the base BC, perpendicular to B C, and meeting P Q in E and F; or by drawing the perpendiculars D F, B G, through the extremities D and B of B D, the other half of the base meeting P Q in F and G.
In the case of the parallelogram, if it be required to make two of its opposite sides equal to a given straight line, as the straight line x in Fig. 43, or two of its opposite angles equal to a given angle, as the angle Y, we must from the extremity of one-half
make the angle DC K equal to the given angle Y, and through D draw D H parallel to c K in order to complete the parallelogram as before.
This process will only be found practicable for the construction of a square equal in area to a triangle when the triangle is a right-angled isosceles triangle; but for any other description of triangle it will be found necessary first to construct a rectangle equal in superficial area to the given triangle, and then to draw a square equal to the rectangle thus obtained. How to do this will be shown presently in Problem XXXI.
By Problem XXX. we are enabled to construct a square equal in area to any number of given squares. Thus, suppose we wish to construct a square equal in superficial extent to the five squares of which the length of the sides of each is represented by the straight lines A, B, C, D, E respectively (Fig. 44). Draw any straight line, F G, equal to A, and at its extremity, G, draw G H at right angles to it equal to B. Join F H: the square described on FH is by Problem XXX. equal to the squares de
scribed on FG and G H. Next draw H K equal in length to the given line c, at right angles to H F. Join K F. The square described on FK is equal to the squares described on K H, H F, or to the squares described on K H, H G, G F, since the square described on H F is equal to the squares described on H G, G F. By continuing this process we at last obtain the straight line M F. The square described on this line is equal to the sum of the squares described on the given straight lines, A, B, C, D, E. Now let us see how far this is of practical value to the artisan. Let us suppose that a cabinet-maker has a number of small squares of veneering of several kinds of choice wood, each square being of a different size, and he wishes to use up this wood in veneering a table or the panel of a cabinet without wasting a single scrap of it. By following the process just described it is manifest that he possesses the means of readily ascertaining the exact area of the square that these pieces will cover, and after finding this, he can, if it be desirable, by Problem XXXI. draw a rectangle equal in area to the square if he prefer this form for using up his squares of veneering, and then arrange his pattern in such a manner that his squares may be worked up without waste. It is also a process that is useful to the maker of floors in parquetry, or to a stonemason who wishes to know how large a square he F can pave with a number of smaller squares of stone or slate of different sizes. Of course in such cases the operator would work to a given scale, and the process might be used as a test of the correctness of the result of the operation by which the whole content of the squares may be found arithmetically, or as one which is far more certain and involves far less trouble than the arithmetical operation, which would be a long and tedious one.
PROBLEM XXXI.-To draw a square that shall be equal in superficial area to a given rectangle.
Let A B C D (Fig. 45) be the given rectangle; it is required to draw a square equal in superficial area to the rectangle A B C D. Produce C D indefinitely in the direction of E,
and on the straight line D E set off DF equal to the side DA, or B C of the rectangle A B C D. Bisect C F in G, and from G as centre with the radius G C or GF describe the semicircle c H F. Produce D A until it meets the arc CHF in K. Then along the straight line D C set off D L equal to D K, and through the points K, L, draw the straight lines K M, L M parallel to C F, D K respectively, and meeting in the point м. The figure DLM K is a square, and it is equal in area to the given rectangle A B C D. If FNOL had been the given rectangle, the same process would have been followed. FL would have been produced in the direction of L, and L C set off on it equal to the side L O of the rectangle L ON F; C F bisected in G; the semicircle c H F described as before, and L O produced to meet the circumference C H F in P. The square drawn on L P is equal in area to the rectangle F L O N. If it be required to draw a square equal in area to a given parallelogram, we have only to construct a rectangle equal to the given parallelogram, and proceed as above. This will be seen from Fig. 45, in which the rectangle A B C D is equal to the parallelogram D C Q R. PROBLEM XXXII.-To draw a rectangle that shall be equal to a given square, and have one of its sides equal to a given straight line.
Let A B C D (Fig. 46) be the given square, and x the given side of the required rectangle, and in this case let x represent the shorter of the two pairs of sides by which the rectangle is enclosed. First produce C D indefinitely both ways towards E and F, and along C E set off CG equal to x, and also along C B set off c H equal to x. Join B G, bisect it in K, and through K draw K L perpendicular to в G, meeting E F in L. Then from the point L as centre, with the radius L G, describe the semicircle G B M. Through the point м draw M N parallel to A D or C B, and through H draw H N parallel to A B or E F, and let the lines HN, M N meet in N. The rectangle C H NM is equal in area to the square A B C D.
When the longer of the two pairs of sides that enclose the rectangle is given, as Y in Fig. 46, produce c D indefinitely both ways as before, and set off c м along C F equal to Y. Join B M, bisect в м in o, and through the point o draw o L at right angles to в M, meeting E F in L. Then from L as centre, with the distance L M, describe the semicircle M B G. Set off along C B the straight line c H equal to c G, and complete the rectangle c H N M by drawing н N, M N through the points H and M parallel to c M and C H respectively.
The learner must remember that the side of a square is a mean proportional between the sides of any rectangle that is equal to it in superficial area; and, therefore, that to find the length of the side of a square equal to a given rectangle, we must set off on the same straight line, but in opposite directions, two lines equal in length to the sides of the given rectangle, bisect the line thus obtained, describe a semicircle on it, and find the mean proportional to the two lines of which it is composed, by drawing a perpendicular from their point of junction to meet the semicircle, as in Problem XIII. (page 192); while, to find the lengths of the sides of a rectangle that shall be equal to a given square, we must draw a straight line at right angles to a line equal in length to the side of the square, and from a point in this line on either side of the line that repre sents the side of the given square, draw a semicircle with a radius equal to the straight line joining the point that is used as the centre of the semicircle and the more remote extremity of the line that represents the length of the side of the given square. The lines intercepted between the other extremity of this line and the extremities of the arc of the semicircle will be equal in length to the sides of a rectangle, having a superficial area equal to that of the given square.
illustration in Lesson XI. (page 353) to understand the structure and relation of each hair to the skin in which it is developed and fixed. The hair is essentially a tubular projection of the cuticle, firmer and denser in its composition, being made up of closely. pressed. elongated, spindle-shaped cells, instead of scale-like, easily-detached ones. It is not, however, produced from the level of the surface of the body, but from a bag or follicle, which is always narrow, and more or less deep as the hair is long or This horny tube dilates at the bottom of its bag to short.
In the higher in's and in all those whose means of defence V ràeir active powers than in defensive armour, the enclose a vascular papilla, similar in every respect to those sense of touch is disbated over the surface of the skin, as in papillae which lie immediately under the surface of the superThe hair itself, like the rest of the cuticle, is Prere such animal may be compared to an island. The ficial cuticle. boundary of its body is the coast-line. Along the whole of this without sensation, as indeed it must be for the comfort of the are placi, at various intervals, places of out-look, just as our animal; but the papilla has not only blood-vessels but nerves, own tight hitle island has been surrounded with Martello and is very sensitive, so that the hair cannot be pulled or moved These stations are few and far between where the in any direction without affecting the sensitive part. Though a coast is rocky, abrupt, and inaccessible, but nearer together furred animal cannot precisely tell the exact point at which it is at those parts where a descent could be easily made, and touched, on account of the length and flexibility of its individual crowded together at the outlets of ports, creeks, and river- hairs, yet the sensation of touch is as truly conveyed to the true The skin, as it is when the pressed ridges of the forefinger of man mouths, through which an active commerce is carried on. cause feeling to be excited in the papillæ beneath them. In one comparison of the extremities of the tactile nerves to Martello towers is the more appropriate, because these have ceased to be respect hairs are even advantageous to the sense of touch, inasof any use in defence, and have become stations of out-look for much as they reach considerably beyond the surface, and thus the coast-guard. So the tactile nerves are, in themselves, no the range of the sense is extended. This advantage is so far protection, but rather, being delicate organs, they need protec- recognised by nature that certain hairs are specially developed tion; for they act as alarmists, awakening and calling up the active which have no other use than that of touch. These may fairly powers to fight in defence of the common country. These two be described as tactile organs. These hairs are usually, and functions of the skin-namely, that of passive defence and active almost exclusively, situated in the upper lip, projecting from the alarm--are complementary to one another: where one is very most prominent part of the muzzle. In quadrupeds the snout efficient, the other is less needed. In the scaled and mailed is of course the most salient part of the body, and is most used fishes, and in such forms as the tortoise among reptiles, and the in investigation. These whiskers, as they are called (though armadillo among animals, the function of sensation is sacrificed they would be better named moustaches), are remarkable for to that of defence; but in the naked skinned animals the sense their length and stiffness, the depth to which their large bulbs of touch had need be very acute. In comparing man with the run into the skin, and even protrude in the internal surface, and lower animals of that class to which he belongs, we find that also for the large nerves that enter the papilla of the bulbs. his sense of touch is, perhaps, better developed than that of any Those coming from the whiskers of a seal as they run together other animal. The lower animals have to sacrifice a certain look like the strands of small cords as they become woven into amount of their surface sensibility to the paramount necessity a rope of tolerable thickness. The animals in which these of being shielded from the cold; or, to put it more truthfully, whiskers are most developed are the carnivora and the rodentia. to the retention of their animal heat. Man has neither the This is not improbably associated with the fact that these are continuous thick coating of hair of the ox, the thick skin of the for the most part, nocturnal animals. Moreover, many of the rhinoceros, nor the dense accumulation of fat below it which is rodentia inhabit holes in the ground, trees, etc.; and many of found in the pig and in the whale. He is only cosmopolitan the smaller carnivora are always poking about in holes and because his superior intellect enables him to clothe and house crannies for prey. It certainly would be an advantage to a fox himself. His nearest relatives among beasts, though much on a dark night to be able to gange with his whiskers the size better supplied with hair than himself, are confined to the of the aperture in a hen-roost before he tried to force his way tropics. Man makes himself at home everywhere, but only by through it; and thus it has been thought that there is a rela becoming a "clothes philosopher." His triple investment of tion between the width of the body and the extreme extent of ordinary, nether, and over clothing, prove him to be an exotic the whiskers. species. He supplements by art the line of defence at those points where nature has left him exposed. The main use of the coating of hair is, no doubt, to defend the brute from the winter's cold, but that which will keep in the heat will keep it out, so that it may also be considered as a defence against the excessive heat of the sun also. Doubtless the universal presence of hair on the heads of both sexes of the human species indicates that in his native home man had more to fear from sun-stroke than from the cold of winter. Besides this, the hair is sometimes a real defence against the rough usage of the outer world. Thus the manes of the lion and the buffalo are real shields both against trenchant blows and the worrying of the teeth of hostile animals. Even the matted hair of the negro is said to be able to resist a tolerably forcible sabre cut. The principal use, however, is, doubtless, to defend from cold; and it is remarkable how this main object is arrived at without much prejudice to the function of touch.
Few solid substances are lighter than hair, even when pressed close; and few substances are worse conductors of heat-so that brutes retain their heat by the aid of a substance which costs them but little in the way of carriage. Beyond this, the springy, stiff, yet soft texture of hair, makes it always permeable to the air; and air, when motionless, is a bad conductor of heat, and adds, absolutely, to weight. Hence on the coldest day, when the thermometer stands below zero, the beast is still surrounded with a layer of warm air, almost equal in temperature to its body. So much to prove its efficiency for its main purpose. Now we have to show how it leaves the sense of touch, if not unimpaired, at least not obliterated. The reader must refer back to the
In birds the place of hairs is supplied by feathers. The structure of these is very wonderful and beautiful, but a description of it would be out of place here, because they are certainly less efficient tactile organs than hairs. Birds' feathers are coarser than hairs; they are less flexible; they are inserted only on certain parts of the body; and since there must be provision made for moulting, they are more definitely cut off from the sensitive skin below. For all these reasons they are not good organs for transmitting the sense of touch, although they are formed in the same manner as hairs. Probably on account of this inaptitude to transmit impressions, they are sometimes replaced by hairs in certain parts of the body; but as a rule the whole of the bird's body is encircled with feathers, which lie overlapping one another, and turned in one direction towards the tail of the bird. in the same manner as tiles on a house-roof. A bird's jaws, instead of being covered with soft, flexible and sensitive lips. are covered with a hard, horny bill, and its legs, though often devoid of feathers, have to be defended by scales or scutes, to prevent the long tendons of their leg muscles being severed. Under these circumstances, a bird enjoys little advantage from its sense of touch. Indeed, it is only in the padded under-surface of the foot and toes, and sometimes in the beak and tongue-when the former is leathery, and the latter not capped with horn-where there can be any provision for the exposure of a sensitive surface. It has sometimes been stated that the heron, as he stands in shallow, muddy water, is guided by feeling the eels twisting in and out, or even sucking his toes. This statement seems rather suited for a fable of the biter bitten than to be regarded as a scientific fact. That the sense is pre
sent in some birds is shown by the fondness of parrots for tickling; but it may be stated that the great activity of birds makes them rely on their far-ranging senses rather than on the circumscribed indications of the sense of touch.
The cold-blooded animals (reptiles and fish) differ from the warm-blooded (mammals and birds), in having for the covering of their bodies no non-conducting or heat-retaining substances. Hairs and feathers are admirable retainers of heat; but scales and scutes, though good to resist blows and pressure, allow heat to pass out or in without much resistance. This, of course, is associated with the fact that reptiles and fish have but little heat to lose. It does not follow, however, that because the body of a fish or lizard is entirely defended by scales, whose free edges overlap the insertions of those next behind them in a manner which is called "imbricated," that therefore they are entirely without the sense of touch. The scales are developed much as the human nails are, and we know that these are themselves insensible; yet they are so intimately connected with the sensitive parts by which they are formed, that the nails are the conductors of acute, and even morbid sensation. The quick of the nail is proverbially sensitive to pain; witness the common phrase of being wounded, or cut to the quick. Reptiles, however, slough at certain seasons, and the old skin, dissevered from the cutis, adheres to them for some time-in fact, until a new and complete armour is formed below. During such periods, and inferentially at all times, the sense of touch cannot be acute. Scaled reptiles may be alive to blows or pressure, but hardly to those sensations of soft touch which convey the most distinct impressions of all to us. These remarks apply with yet more force to the hard, stony, surface of the backs of crocodiles. The under side of the body of crocodiles is leathery rather than stony, and has fewer stony masses on its surface, and this is therefore sensitive. Sir Emerson Tennent gives an amusing account of a cayman, which he surprised before it could make its retreat. The Ceylon crocodile threw itself on its side, and feigned death; but when it was tickled under its arm it found the process too much for its gravity, and finally got up and hobbled away. As we before remarked in the article on taste, the tongue is made use of by serpents and lizards to touch objects with; and this is probably its main, if not its only use. In conformity with the assertion that nocturnal animals often have specially modified organs of touch, we find that certain nocturnal tree-snakes have their snouts prolonged into tactile
The large majority of fish are completely closed in by plates and scales. With few exceptions even the lips are hard and dry, so that they need to have some special organs of touch. Sometimes certain rays of the fins are detached from the oarlike parts, and become long styliform organs of touch. When this is the case, they are clothed with soft parts, which are well supplied with nerves. Thus, in the gurnet three soft rays are told off from the front of the pectoral fin, to form feeling fingers. It is curious that in a creature so far removed from man we have the same parts modified to the same use, though in almost all the intermediate animals this part has a different function. In the angler two rays detached from the back fin, and situated on the top of the head, have this function, but the nse to which he puts these feelers is remarkable. One of the feelers has at its end a flattened, shining, and flexible adjunct, and this is used as a bait, just as a silver strip is used by the troller. The angler is rapacious, but sluggish; he therefore lies on the bottom, with his huge, ugly mouth wide open, and stirs up the mud with his fins to conceal himself, while he drops his sensitive bait before his mouth and keeps twitching it about, until he feels some hapless fish begin to nibble, when he makes a forward rush and closes his mouth upon him. The whole of each of the four limbs of the lepido-siren are converted into organs of touch. For the most part, however, the limbs of fish which correspond to our legs and arms are entirely devoted to locomotion, while quite new structures are developed for them to feel with. These special tactile organs are called barbules. They are placed on the head, and generally at the fore part of the jaws. When on or under the lower jaw they may be single; but they are more often, and when on the upper jaw always, in pairs. Two instances are given in the illustration: the one shows how they occur in an eel-like fish, and the other in an ordinary-limbed fish. The single medial barbule under the jaw of the cod is a familiar example. It is supposed that a cod
which was blind when caught had obtained its food so well by the aid of this that it was quite in good condition. Barbules are well adapted to the purpose of touch. If in any other way nerves were conveyed through the scaly covering and exposed, these delicate structures would be liable to be injured by the impact of hard external bodies, which would be crushed between them and the hard and underlying scales; but since the main nerve of these barbules accompanies a cartilaginous core, and since it springs from a single point to be spread upon a flexible pillar which hard bodies would drive before them, the chance of having the nerve crushed is much reduced. Barbules are for the most part found on the jaws of grovelling fishes like sturgeons and barbels, which feel along the bottom for all kinds of garbage which may have sunk there.
The mollusca have received their name from their general character of softness; mollis being the Latin adjective for soft. This name was given them by Cuvier to contrast them with the hard-coated insects and crustacea which belong to the subkingdom articulata. Hence in those species which are not provided with a shell, and in the exposed parts of those species which have this protection, there is a soft, sensitive skin. The skin, however, in this sub-kingdom has often superadded to the functions which it possesses in vertebrata the functions of respiration and of locomotion. Even those parts where the sense is more or less localised have so many other offices to which the sense is secondary or subservient, that it would lead us too far from our subject to describe them. It is true that the gasteropoda have horns as special tactile organs; but we find in the cephalopods the sense of touch is intimately combined in the arms with the elaborate apparatus for grasping and holding their prey; and in the brachiopods the sense is united with the organs for breathing and keeping up currents in the water. We must, therefore, avoid going into details in reference to them. It may be stated generally, that the slower an animal moves, and the more fixed its station, the more will its sense of touch be developed in proportion to the other senses. Hence the sense of touch is well developed throughout this sub-kingdom. Soft bodies are ill-suited to energetic motion; but soft bodies are well adapted to receive tactile impressions. In those animals of this sub-kingdom which are wholly fixed, the organs of touch are multiplied; and in the lowest class of all there is a horseshoe-shaped or circular series of tentacles round the mouth, which are extremely sensitive. This arrangement of feelers around the mouth is so general a character of fixed animals, that there is a striking similarity between the outward form of these lower molluscs and the fixed animals of the sub-kingdom colenterata, although the essential organs are quite different. The articulata (though some of them are soft-skinned) are for the most part covered with a hard, horny covering, which is as resisting as plate-armour. It is therefore necessary that these animals should have special organs of touch. We have already referred to those of the lobster and its tribe in a former number. Insects have, developed from their heads and mouth-organs, jointed rods, which have nerves of touch running to them and up into them. These jointed rods are covered with hard, horny matter, like the rest of the body; but sometimes the last joint exposes a naked membrane, and where this is not the case, the jointed and therefore flexible nature of the organs make them capable of receiving impressions of touch, and of measuring the dimensions and resistance offered by external objects. The normal number and position of these organs will be seen in the illustration. There are two long, many-jointed ones jutting from the head; these are called the antennæ. Another pair (or pairs) spring from the lower lateral jaws; they are called the maxillary palpi. Another pair (or pairs) spring from the sides of the lower lip; these are called the labi palpi. The soft-skinned spiders have no antennæ or labi palpi, but their maxillary palpi are so long and large as to look like legs.
The echinoderms, or sea-urchins, are so enclosed in their more or less spherical boxes of hard shell, that a casual observer would suppose them to be unfeeling wretches, capable of inflicting wounds with their long spines, but insensible to softer emotions. This is not the case, however, for they can protrude through the small holes which perforate the shell and occupy five double meridional bands of their globular boxes, a multitude of soft, tubular, sucking feet, to each of which there runs a nerve.
The sea-anemone, with its streaming feelers, lives by feeling; and the whole sub-kingdom to which it belongs is