temporary lateral, together with a portion of that set apart for its own exclusive use. Between the mesial surface of this tooth and the median line there was not less than one-sixteenth of an inch of space to spare; and about the same between the distal surface and the canine. There was not, at the time this set of models was made, room enough to accommodate the right permanent lateral; nor would there have been even if all the unoccupied space had lain on the distal side of the central. With the exception of the lateral, the temporary teeth were all in place. The first permanent molars were in their proper positions and in active service.

Here surely, some would have said, was contraction of the jaw and the promise of irregular arrangement of the teeth.

In the lower jaw several changes showed themselves quite plainly. Within the period of six months the second right temporary molar disappeared, the left permanent lateral incisor at

tained nearly its ful length, the right just pierced the gum. Both first permanent molars were in place and, like their opponents. in the performance of duty. In this jaw there was no appearance of contraction; neither was there the promise of irregularity of the teeth.

The third set of models was made in November, 1875, about two years later than the set last described.

In the upper jaw we found four permanent incisors, fully erupted, and separated from each by one thirty-second to onesixteenth of an inch; four temporary and two permanent molars. Here, as in the jaw when the second set of models was made, was the appearance of contraction of the jaw and the promise of dental irregularity. But despite this unfavorable look of the case there were several things wherewith to offset it; the canines

were not in sight and could hardly be outlined in the jaw by means of the finger; there was some space between the incisors, and still more between the laterals and first temporary molars ; the jaw was fairly developed; the child was in the way of rapid growth.

In the lower jaw the last temporary molar was missed; the four permanent incisors and first permanent molars were fully erupted; the left permanent canine was half out; the right just ready to cut the gum. There was ample room on either side for the bicuspids and no indication whatever of contraction or irregularity.

FOURTH MODELS.

IV

IV

The fourth set of models was made from impressions taken last

month (May, 1876.)

The upper jaw has changed but little since the third set of models was made. Though somewhat decayed and broken down, all of the temporary molars still remain in place. There appears to have been but little change in the jaw, either as to growth or development, and the chances of dental irregularity appear better than ever.

The lower jaw shows changes only in the eruption of the canine teeth. The left is fully erupted; the right about half the length of its crown.

It will be remembered that in one of our quotations from Kingsley, that author says, "a crowded and abnormal condition

is not as likely to show itself with any of the other teeth as with the canines." The prominence of the canine teeth is due chiefly to want of growth and development of the jaw; though in some cases, as Kingsley elsewhere suggests, it may be brought about by the forward movement of the first permanent molars into the space previously occupied by the temporary molars. But this forward movement of the first permanent molars is, in some cases, apparent rather than real. In the case of early extraction of the second temporary molar, the first permament molar tips forward or overhangs the yet unerupted second bicuspid. It may be urged that the second bicuspid is not far enough advanced, either in size or in its progress toward the surface of the jaw, to offer much resistance to the forward movement of the molar. To this we answer that the crypt of the second bicuspid will accommodate a fully developed tooth-crown; that this crypt, because of its compact structure, of itself offers a somewhat formidable obstruction to the advancement of the molar; and that any antero-posterior measurements as to the relative distances between the cusps of the anterior teeth and those of the molars, are deceptive, unless the measurements are made at stated intervals and the differences between what may be termed the angles of eruption allowed for.

In the case now under consideration measurements show no advance of the first permanent molars toward the anterior teeth. The principal measurements (see Fig. IV) were made betweer these points: the mesio and disto-incisive angles of the permanent central incisors and the line or fissure between the buccal

cusps of the first permanent molars; the line of juncture of enamel and cement on the lingual surface of the incisors and various points of the same line of the molars; also molar and molar to determine their approach toward each other. No movement, except eruptive movement, on the part of the permanent teeth could be discovered. Had it not been that the molar teeth of the lower jaw interlocked well with the corresponding teeth of the upper, there might have been some forward movement on the part of the former. This is a point that should not be lost sight of; certainly not by those who are indissolubly linked to the old and prevalent notion that premature extraction of the temporary teeth is necessarily followed by contraction of the jaw and irregular arrangement of the permanent teeth.

It is evident that in the case of a full lower denture, the molars of which have well-developed cusps, the upper molars, if normally articulated with the lower, cannot possibly move forward, even after the removal of every tooth anterior to them. The perfect adaptation of the upper and lower molar cusps is alone a sufficient obstacle.

And now we are ready to ask-Has not contraction manifested itself in the upper jaw, and possibly in the lower?

If the term contraction used in the sense of retarded growth or want of growth proportionally to the wants of the teeth, we are ready to answer in the affirmative. It certainly has in the upper jaw; it may have done so in the lower, but the evidences of it, if they exist at all, are so obscure that we may dismiss the lower jaw entirely from consideration.

We admit that there is not now, and not likely to be, sufficient room in the upper jaw for all the permanent teeth.

In how many and what ways will irregularity of the teeth of - this jaw manifest itself? First, the canine teeth will erupt quite prominently, so as to deserve and receive the name of "tushes;" second, the first bicuspids and laterals will be greatly depressed (the latter slightly turned so as to lap the centrals), directly by the canines, indirectly by the muscular structure of the lip; third, the right central incisor will lap the left.

And will not this condition follow as a consequence of the early loss of the temporary teeth? Not at all; for were this the