« AnteriorContinuar »
large discs of the Triton, and know fresh prolongations are thrown out; not if Mayer's observation has been thus, as you watch it, you perceive confirmed by any other microscopist. it assuming an endless succession of But there are other grounds on which forms, justifying the name of Proteus we should be disposed to accept the originally bestowed on it. So like fact of the nucleus being normally the Ameba is the colourless bloodpresent, and not simply the result of corpuscle, that many observers have coagulation : the chief of these is, not hesitated to adopt the opinion that in the embryo of a mammal we that these corpuscles are actually discover nuclei in the discs, whereas animalcules, and that our blood is a in the adult animal no nuclei are dis- select vivarium ; an opinion which is coverable, even after long exposure not very tenable, and is far from to the air ; and the philosophic zoolo- necessary for the purposes of explagist well knows in how many minute nation. We may admit, and the particulars the embryonic state of the point is of profound philosophic inhigher animals represents the per- terest, that the blood-corpuscles are manent state of the lower. In the analogous to the Amebæ, without discs of all adult mammalia the admitting them to be parasites. Connucleus is absent ; what has some- sidering the wondrous uniformity in times been mistaken for it is simply the organic creation, considering how a central depression of the disc, which Life seems everywhere to manifest gives it the form of a bi-concave lens. itself under forms which through Nevertheless, although the nucleus is endless varieties preserve an uniabsent in the adult, it is present in formity not less marvellous—so few the embryo; and I have seen it in and simple seem to be the laws of the blood of a young kitten.* organic combination there is nothing
There are other bodies in the blood at all improbable in the idea that as beside these, and they are known as the Amoeba is the starting-point of the colourless corpuscles, which consist the animal series, an analogous form of two, if not three, different kinds. may also be the starting point of the The true colourless corpuscle (and it animal tissues. The blood is, we will be convenient to confine the know, the source from which the term disc, or cell, to the red corpuscle) tissues draw their substance; the is much larger than the disc, and corpuscles seem to be the embryonic seems to be a round vesicle contain- forms of the blood-discs in vertebrata, ing a number of spherical granules and constitute the only blood-cells of imbedded in a gelatinous substance. the invertebrata; we may therefore This corpuscle has the property of regard the development of the tissues spontaneous expansion and contrac- as beginning, not indeed in an Amoeba, tion, which forcibly reminds the but in a form analogous to that of observer of the contractions and ex- the Amcba. We are further dispansions manifested by that singular posed to this point of view by finding mieroscopic animalcule, the Amoeba, that not only is the blood of the inprobably the very simplest of all vertebrata (i.e. of forms which may organic beings. The Åmøba is a be regarded as embryonic in refersingle cell : it has no “organs” what- ence to the higher animals) princiever, but crawls along the surface pally constituted by these Amebaby extemporising an arm or a leg out like cells,t but that the very subof its elastic substance, which arm or stance of the fresh - water polype leg is speedily drawn in again, and sometimes breaks up into several dis
* Mr Wharton Jones, one of our best investigators, says that the blood of the elephant and the horse contains a few of these nucleated discs. Nasse has seen them in the blood of pregnant women, and Mr Busk found one in that of a man. Kölliker disputes the accuracy of these observations, and thinks that in each case the nucleus was produced by some alteration of the contents. At any rate, the presence of nu. cleated discs is the indication of physiological inferiority, and we may perhaps find them in certain cases of disease.
+ They have been seen in mollusca, crustacea, and insects. Last autumn I saw them in the beautiful transparent Corethra larva.
tinct cells, which can in no respect The blood of the invertebrated animals be distinguished from Amoebæ.* contains coarse granule-cells, which pass This view seems also borne out in forward to the condition of fine granuleanother direction ; for, following cells, and reach the utmost perfection they Auerbach's directions, I have been
are there to attain in the colourless nu. lately accustomed to obtain Amcebæ cleated cell of the first period of man. when I wanted them, by simply ex
In oviparous vertebrated animals, the posing organic tissues, in a state of the red nucleated cell arising, and in
development is carried a step further, decomposition, to the prolonged in- them it stops at this, the second period. fluence of sunlight and water; and . In mammals the third stage is reached as far as careful experiments could in the red non-nucleated disc, which is warrant a conclusion, the conclusion therefore the most perfect form." + was that these Amcebæ were the products of a recomposition of the
The resemblance here indicated decomposing matter, and not the between the transitory forms of the products of ova or spores. This is
, blood in the higher animals, and the however, open to question.
permanent forms of the blood in the The corpuscles are not numerous
lower animals, points at a hidden law in healthy human blood, and play of organic combination which will but a secondary part, unless we
perhaps one day be detected, and assume, with many physiologists,
which will effect for Biology as much that they are the early stage of the
as the law
definite proportions ha red discs. Professor Draper speaks have studied the development of
effected for Chemistry. No one can unhesitatingly to this effect. He says there are three periods in the his animals, without being profoundly tory of our blood cells. Those of the impressed with the conviction that first period originate simultaneously
there is something deeper than coinwith, or even previously to the heart cidence in the recurrence of those ---these are the embryonal cells, they forms, however transitory, which are colourless and nucleated. By process of internal deliquescence,
tion of some animals simpler in orthey are developed into the cells of ganisation. the second period, which are red,
The colourless corpuscles are found nucleated, and oval, like the normal by Moleschott to be far more numercells of reptiles. The cells of the
ous in children than in adults. The third period replace these, “the tran- difference between the blood of youth, sition being clearly connected with manhood, and old age, is but trifling the production of lymph and chyle yet there is a continual decrease with corpuscles.” This change takes place age. Women, in normal conditions, at the close of the second month of have fewer corpuscles than but
men ; fætal life ; and from henceforwards during pregnancy, and other periods, no change is observable ; the cells the quantity increases, without, howcontinue to be red, bi-concave, non
ever, reaching that in the blood of nucleated, and circular.
children. Albuminous food increases
the quantity “The cell of the first period is there
After making ourselves acquainted fore spherical, white, and nucleated ;
with these blood-cells and their histhat of the second,
red, disc-shaped, and tory, which even the amateur may nucleated ; that of the third, red, disc
do with pleasure and profit, we shall shaped, bi-concave, and non-pucleated. have to meet the question—Is the The primoidal cell advances to develop blood alive —a question often dement in different orders of living beings. bated, and not without its interest to
* Sometimes, but often not ; so that the phenomenon probably depends on the state of the animal. ECKER describes a "contractile substance" in the Hydra, which be likens to the Ameba, but his gures do not at all resemble the contractile cells which I saw, and which, indeed, were so like Am@bæ, as to make me believe at first that the Polype had swallowed them.
+ DRAPER : Human Physiology, p. 115.
Lietres primum vivens, ultimum mo
the speculative mind. Harvey * held Let us now turn from the floating the blood to be the “primigenial and solids of the blood to the plasma in principal part, because that in and which they float-from the cells to from it the fountain of motion and
As the blood circulates pulsation is derived ; also because in the vessels, we see that there is the animal heat or vital spirit is first nothing solid in it but the discs and radicated and implanted, and the corpuscles; yet no sooner does it soule takes up her mansion in it." pour from the vessels, than part of the We see here the influence of the liquid itself becomes converted into ancient philosophy. Harvey further a trembling jelly, from which a yellow declares, “Life consists in the blood fluid slowly separates. The jelly-like (as we read in Holy Scripture), be- mass has many of the red discs imcause in it the Life and Soule do first bedded in it, and is called the clot ; dawn and last set.
The blood the yellow fluid is the serum ; the is the genital part, the fountain of whole process is called the coagula,
tion. The general phenomenon was
known to the ancients—indeed, it Harvey's views were taken up, could not have escaped observation ; with modifications, and argued ear- but we must descend as far down as nestly by Hunter, in his celebrated the seventeenth century before meetwork On the Blood. It is more ing with a physiologist who had than twenty years since we read that more than this general knowledge; work, and not having it now at hand, and there we meet with Malpighi,t we can give no exposition of its who washed the clot free from all views. The constant objection urged the red discs, and found that the against Hunter by his contempora- white substance which then reries and successors, was the inability mained was of a distinctly fibrous to conceive a living liquid ; but texture. Borelli, at the same epoch, Milne Edwards meets this by say- declared that this substance was ing that it is not the liquid which is liquid in the blood, and coagulated alive, but the cells floating in that spontaneously when the blood was liquid, and these he regards as or. drawn from the veins. This opinion ganisms. The reader must feel that is now universal. Ruysch discovered the discussion of such a question that by whipping the blood as it cannot be brought to an issue, unless poured out, the whipping-rods were preceded by an accurate definition of covered with a mass of white elastic the terms employed. What is meant filaments, exactly similar to the subby the blood being alive? If it be stance obtained by washing the red meant that an organic structure, discs from the clot. This substance, having a specific composition, and the only one among those contained passing through a definite cycle of in the blood which has the property changes, such as birth, growth, de- of spontaneous coagulation, has, since velopment, and death, can truly be the days of Fourcroy, been named said to live, then blood, which mani- fibrine; and, until recently, it has fests these cardinal phenomena of been held to be identical with the life, must be pronounced to be alive. substance of muscular tissue : thus, This, however, no one would think the formation of muscles seemed of denying. But if it be meant that easily explicable, as the spontaneous blood has an independent vitality, coagulation of the fibrine, to those unlike the vitality of any other tissue, theorists who delight in simplifying a vitality which can be manifested organic processes, and who are apt apart from the organism, the opinion to accept a phrase as an explanation. seems to us wholly untenable. Blood We now know that the fibrine of the is vital, and has vital properties; but blood is not the same substance as so has every tissue of the body, and the fibrine of muscle, and this latter in no sense can we attribute to it in- is therefore called musculine or syndependent life.
* HARVEY : Anatomical Exercitations concerning the Generation of Living Creatures, 1653. Exc. 51, p. 276.
+ MILNE EDWARDS : Leçons, i. 115. MALPIGHI: Opera Omnia, 1666, p. 123.
Why is the fibrine not coagulated four instances; all these were cases in the blood vessels, seeing how rapių- in which death ensued from slow arly it coagulates out of them! Pro- rest of the respiration. Drs Peters, fessor Draper thinks that “nothing Goldsmith, and Moses, three Amerimore takes place in blood, which has can physicians, have published a reþeen drawn into a cup, than would port on the appearance of the blood have taken place had it remained in in twenty cases of death resulting the body. In either case the fibrine from
the excessive use of ardent spirwould have been equally coagulated. its. In every case the blood was The entr og of the cells is a mere fluid and dark, was of a cherryaccident. The hourly demand for juice appearance, and showed no fibrine amounts to sixty-two grains; tendency to coagulate. Majendie a simple arithmetical calculation will produced a fluid state by injecting show that the entire mass of the putrid matters into the veins of aniblood would be exhausted of all the mals. In deaths from the narcotic fibrine it contains in about four poisons, from delirium tremens, tyhours, so that the solidification of the phoid fever, and yellow fever, the fibrine must be taking place at just blood is generally described as thin as rapid a rate in the system as after and uncoagulable. Dr John Davy it has been withdrawn. No clot found the blood fluid and uncoaguforms in the blood vessels, because lable on exposure in cases of drownthe fibrine is picked out by the mus- ing, hanging, suffocation from the cular tissues for their nourishment as fumes of burning charcoal and effufast as it is presented, nor would any sion of blood into the pulmonary clot form in the cup if we could by air-cells.” * any means remove the fibrine gra- Dr Richardson also states a fact nules as fast as they solidified.” This quite inexplicable at present, nameingenious hypothesis rests entirely ly, that not only is the blood drawn on the assumption that the fibrine is by a leech uncoagulable, but that the momently picked out by the muscu- bite of the leech seems to affect even lar tissues; an assumption which the blood which remains in the bitseems to us more than questionable, ten vessels, since the blood continues for if the plasma of the muscles be to flow much longer from the wound examined i.e., that part of the blood than from a wound made by the which has passed through the walls lancet; and this can only be because of the vessels for the nutrition of the the wound is not closed by coagulamuscles-no coagulated fibrine will tion. Dr Richardson sums up his be found there ; whereas, in almost numerous experimental results in every case of the escape of serum into the following propositions : - The one of the cavities, or into the sub- power of coagulation is reduced in stance of a tissue, the fibrine is found proportion to the reduction of the coagulated. Against the hypothesis temperature, and is accelerated in let the following facts suffice : In the proportion to the elevation of temblood of starving men, and in that of perature. Blood may be frozen, and men suffering from inflammatory it will then remain uncoagulated ; fever, the amount of fibrine is in- but on being thawed, and exposed to creased; so that instead of fibrine a higher temperature, the process of being picked out from the blood to coagulation begins. Water produces nourish the muscles, it seems to be no effect, unless it be added in exthrown into the blood from the waste cess, when it retards coagulation. of the tissues. Further—the blood, Any fluid denser than blood retards under certain circumstances, will not coagulation. Free exposure to air coagulate at all; yet the fibrine is quickens coagulation, so also does not picked out.
exposure in vacuo. Exclusion from Morgagni,” says Dr Richard- the air retards it. Agitation in the son, had described the blood open air quickens, in a closed vessel as quite fluid after death in only retards, coagulation.t
RICHARDSON. The Cause of the Coagulation of the Blood; 1858, p. 34. + Ibid., p. 228.
We may put our question in an- however, which are not cleared up by other form, and instead of asking, this hypothesis. We do not see how why the blood does not coagulate it accounts for the blood remaining in the vessels ? ask, why it coagulates fluid, even after exposure to the air, at all? The question has frequently in cases of death by drowning and been put, and answered in very con- hanging. It would be necessary that tradictory terms. In the form in Dr Richardson should show either which it is often put, it seems to us that hanging caused a complete renot less idle than to ask why roses moval of the fibrine, or that it prehave thorns, why the cohesion of vented the evolution of ammonia on iron is greater than that of clay, or exposure to the air. Until one of why stupid querists are not enter- these points is proved, the difficulty taining companions? Fibrine coagu- will remain. In sone researches into lates, because it is the property of the history of the blood in the animal fibrine to coagulate, and would al- series, I found the blood of many ways do so spontaneously, were there species of Mollusca quite incapable not some obstacle present. We may of coagulation ; but whether this destudy, the conditions which assist, pends on the absence of fibrine, or on and the conditions which arrest this the presence of any solvent, not votendency, but it is hopeless to in- latile, was undetermined. quire into the cause of the tendency. Hunter declared that the blood of
It is certain that the blood would men and animals killed by lightning remain fluid were there no fibrine did not coagulate. The assertion present; but this fibrine has a spon- has been often repeated; yet from taneous tendency to coagulate, which the experiments of Scudamore and can only be prevented by the pre- Milne Edwards, we are forced to resence of some solvent. What is that ject the idea : the latter has repeatsolvent ? The researches of Dr edly killed birds by an electric disRichardson satisfactorily establish charge, and found their blood as some points which go very far to- coagulable as that of other birds. He wards a demonstration of the true adds, however, that “in certain cases cause, namely, the presence of am- the blood is evidently less coagulable monia in the blood. He shows, in in individuals struck by lightning ; the first place, that ammonia does and this peculiarity is observed in preserve the fluidity of the blood, if connection with a remarkable cadait be present in quantities amounting veric rigidity, so that I am led to to 1 in 8000 parts of blood contain think it may depend on the solidifiing 2.2 per thousand of fibrine. He cation of a portion of the fibrine in shows, in the second place, that the the capillaries, rather than on the blood does normally contain this yo- transformation of that substance into latile alkali, which is rapidly given one not coagulable. This rigidity is off during coagulation. And he sometimes so great in those struck shows, moreover, that the causes by lightning, that the corpse reinains which retard coagulation are causes standing in the position in which it which obstruct the evolution of am- was struck.” monia, whereas the causes which Before concluding our description favour the evolution of ammonia of the blood, we must glance at its accelerate the process of coagulation. chemical composition ; for if the Finally, he shows that if the vapour microscope reveals it to be far from arising from blood be caught in a a homogeneous fluid, chemical anavessel, and then passed through an- lysis further assures us that it conother mass of blood, the coagulation tains water, salts, sugars, fats, and of this second mass is suspended. albuminates. In spite, however, of The numerous and ingenious experi- numberless analyses made with the ments by which Dr Richardson has greatest care, our present knowledge established these important propo- is only approximative; the excessive sitions must be sought in his work, difficulty of making an unexceptionwhich gained the Astley Cooper able analysis being acknowledged by prize.
all who have attempted it. We There still remain some difficulties, know tolerably well what the elemen