It would be evident from the preceding data that the rates of growth are not uniform with every part and organ of the animal's body. To summarize the whole data, however, it would be concluded that the rate of growth in the body weight during the fetal period and directly after birth is especially pronounced and that the increases in the weights of every internal organ was larger than those in the other parts of the body. As shown in Table 26, the relative growth rates also differ between each part and organ of the body. The largest α value obtaind is 5.02 in the body weight in animal's fetal period, followed by 2.42 in the body weight after birth of the animals. (Fig. 26) As for the growth rates of bones, the value α of the lower extremities is comparatively large showing the values 1.41 to 1.58, while that of the upper extremities slightly falls behind with the values 1.21 to 1.28. (Fig. 41) The bones in the head and face are poor in the growth rate in comparison to the growth rate of body length showing 0.52 to 0.89, values smaller than 1.0. Of the relative growth rates of the internal organs, the smallest is the value 0.58 for the lung, followed by 0.99 for the heart, both showing growth lesser than that of the body weight. On the contrary, the values 1.06 for the spleen, 1.12 for the stomach and the liver, 1.15 for the kidneys, 1.24 for the thymus, these values show that all these organs slightly exceed the body weight in the growth rates. It has been known from reviewing the works of previous investigators that Shimizu had also studied the coefficients of relative growth in albino rats utilizing the combined data accumulated by Negishi and Watanabe concerning the tail, by Tappe concerning the body weight and by Donaldson concerning the various organs. The α values 2.28 to 2.29 which Shimizu has given as the relative growth coefficient of the body weight against the head to tail-root length is fairly comparable with the author's value 2.42. Unfortunately no report being available as to relative growth of any part or organ of the rat embryo, the present author's value 5.02 was here given which showed a vigorous growth rate occurring in the fetal life of the animal. Of the relative growth rates of various internal organs against the body weight, Shimizu, concerning the heart, has given the values from 0.77 to 1.03 regardless of sex difference of the animal, and Clark has given the value approximately of 0.8 in the mice, rabbits and dogs. These are closely comparable with the author's value 0.99. Of the lung Shimizu, in the albino rats, gave the values from 0.70 to 0.84, Brody, in the dog, 0.85 and the present author 0.58. Of the stomach Shimizu gave values from 0.63 to 1.34 in the albino rats, Brody 0.72 of the stomach and the intestine in the dogs and the present author 1.12 in the albino rats showing a slight difference present between these data. Of the liver Shimizu gave values from 0.75 to 1.81, Brody 0.7 in the dogs and the present author 1.12, an intermediate value of Shimizu's data. Of kidneys Shimizu gave values from 0.81 to 1.75, while the present author gave 1.15. Of spleen Shimizu's value were 0.93 to 1.56 and the present author's 1.06. As shown above, the comparison of the author's data on the relative growth rates of internal organs against the body weight with those of the previous authors proves that there is general agreement between these except minor differences observed between two or three different organs. According to Shimizu's opinion the α value of the internal organs did not change appreciably after the animal's body weight reached approximate value of 35g, and Donaldson added further that 35g of body weight was gained at the 34th to 35th day after birth of the animal and that this corresponded also to the 3rd molar eruption. The present author also confirmed that the animals weighed about

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In view of these facts, we undertook to examine the tooth and the adjacent tissues in albino rats which were given cortisone acetate and were subjected to severe degenerative atrophy in the adrenal cortex. Results ; 1. The adreno-cortical degeneration caused by over dosage or continual dosage of the hormone proved eventually fatal to the animal. 2. The histological findings in the tooth and the surrounding tissues by cortisone administration closely resembled to those found by hypophysectomy. The main findings were circulatory disturbance followed by degenerative changes which affected the developmental process of hard tissue, resulting in particular in the disturbed calcification of dentine.

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The splitting lines in the soft tissues have been studied by Otto Burkard (1903), Klaus Niessing (1935), Fukui ('36), Renri ('51) and other investigators. Report, however, is not available with regard to the splitting lines of the shell membrane of eggs. The present report deals with the experimental observations conducted on the splitting lines of shell membranes obtained from the eggs of domestic fowls, domestic ducks and quails. The egge for the experiment were hard-boiled, then cooled by the water. The shell was then either removed carefully with finger tips from the egg or dissolved of the egg by means of 5 percent hydrochloric acid to expose the shell membrane. The exposed shell membrane was then punctured. The shell membrane is made up of two layers of sheet, upper and lower, and the upper layer was first observed before going to the lower one. The results of the observation were summarized as follows. 1) The running courses of the splitting lines developing in both layers of the shell membrane are perfectly idetical. 2) Viewing the egg with its blunted end directed up, the splitting lines ran like slanting streaks from upper left to lower right direction around the body of the egg. 3) Viewing the egg with its blunted end directed up, the splitting lines at both the blunt and tapering ends of the egg were observed forming anticlockwise spirals, the degree of curvature of the one at the blunt end being more intense than at the tapering end. 4) As to the reason of this spiral formation at both ends of the egg the author is of the opinion that the screwy folds lining the inside surface of the oviduct would be responsible for imprinting the spiral streaks on the surface of just forming shell memdrane of the egg while it is passing there. 5) Further, as to the reason of occurrence of irregular mass of the splitting lines on both ends of certain eggs the author is of the opinion that it would depends on sizes of the egg, because, as the experiments have shown, the egg of domestic duck, the largest of the three, has the irreglar mass of splitting lines in the center of both ends and the medium-sized egg of domestic fowl has also the similar pattern of splitting lines but mingled with trace of spiral formation and finally the egg of quail, the smallest of the three, shows no sign of irregular mass of splitting lines. It seems probable that larger mechanical force of the folds in the oviduct exerted upon larger bulk of the egg during its passage there would cause the formation of the irregular splitting lines at both ends of the egg, a disturdance of the growth orientation in the shell membrane manifested as its direct functional response against the extrinsic forces involved.

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The line systems occurring in every vertebral bones of rabbits have been studied in detail, and the following general patterns have been confirmed to occur in these bones. 1) The line system domynated by the contour of each vertebra : This system seems to constitute the basic form because all the remaining line systems are developed running along with it. Hence, in broader sites of the bones where the contour assumes triangle form concentric triangular line patterns are sometimes made, and in depressed sites of the bones loop-like line patterns centering around the middle of the depression are sometimes observed. 2) The longitudinal line systems running up- and downwardly through the corpus vertebrae. 3) The line systems converging toward the end of each process, or to say conversely, the line systems diverging from the end of each process toward its root. 4) The line systems encircling foramens of the bones.

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The development of the mandible was studied in the hatching embryo, the chicken and the adult domestic fowl, and the results obtained are summarized as follows. 1. The constituent bones of the mandible include Dental, Supraangular, Splenial, Gonial and Angular. The last mentioned bone, however, lacks independence because it fuses with the Articular (at the Processus angularis internus) in the adulthood of the animal. Of the anlages of the coverning bones, those of the Supraangular and Angular appear at seven and a half days after hatching, the Dental at 8 and a half days, the Splenial at 9 days and the Angular at 10 days after hatching. Completion of the covering hones : These bones are constructed into their mature forms within 20 days after hatching, but the time needed for total completion including that of the Articular bone is 3 months after birth. If, further, the formation of the mandibular canal and the fusion of each constituent bone are therein included, the time needed for is one year after birth. 2. The formation and completion of the Articular bone : The Articular bone is formed and completed by cooperation of enchondrous and intramembranous ossifications by 3 months after birth. 3. Formation of the mandibular canal : This is made primarily by intramembranous ossification at the posterior part of the Meckel's cartilage which is then gradually fused with the Supraangular. 4. Formation of the Angular bone : The anlage of the bone develops on the 10th embryonic day at the inner side of that portion corresponding to the root of Processus angularis internus, and by the 11th day a thin layer of new bone is deposited along the process, later to increase the bulk gradually. On the 15the embryonic day cartilage cells occur on the posterior dorsal part of the bone facing the process, and on the 20th day a part of the bone is already fused with the process. By 2 months after hatching the whole constituent bones become completely integrated so that no further discrimination is feasible. 5. Fusion of the constituent bones and how it occurs : Until 6 months after birth the constituent bones are packed together dorsoventrally and in-and outwardly, but by the 12 th month after birth they are almost fused. The fusion takes place as metaplasmatic bone formation especially with regard to the Gonial, Supraangular and the posterior part of the Angular fitting into the concavity on the ventral side of the Articular. 6. Later course of the Meckel's cartilage : After the formation of the Articular bone, the remaining cartilage gradually shorten its antero-posterior length by intramembranous ossification arising from its front and rear peripheries.

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Two types of apparatus have been available for measuring the tooth mobility : one was devised by Dr. Fuse and the other by Drs. Kimura and Ishibashi, the latter being an application of dial gauge generally used in engineering. The author, for his own purpose, undertook to improve the Fuse's instrument for more accurate and more magnified measurement of tooth mobility and has succeeded in making the one with 52.8-fold magnification of tooth mobility. This was named Fuse-Urakami Tester according to the agreement between two authors. By the trial measurements of tooth mobility using Kimura-Ishibashi tester and Fuse-Urakami tester in parallel, it was noticed that besides four common factors which had been regarded to have influences on the tooth modility, i. e. the length of tooth root, the length of tooth crown, the dimension of tooth root surface within the alveolar bone and the breadth of periodontal membrane, four more factors had to be taken into concideration, i. e. the depth of gingival pocket, the changes in elasticity of fibre of periodontal membrane, the changes of rotating axis of tooth root and the errors due to difference of instrument used for measurement. It was generally accepted that the depth of gingival pocket ranging from 1 to 2 millimeter was physiologically normal. Our experiments, however, have shown that the teeth surrounded by the gingival pocket 1 to 2 millimeter deep were already losing their normal elasticity which is indispensable in the masticatory function. After the preliminary experiments the following items were studied, i. e., variability in the tooth mobility measurements due to such various factors as (1) difference of instrument used, (2) the position of load applied on the individual tooth, (3) magnitude of the load applied, (4) the direction of the force exerted forward and backward, (5) sex difference, (6) right and left half of dental arch, (7) difference between mandibular and maxillar teeth, (8) age difference and lastly, (9) the depth of gingival pocket. The results obtained were summarized as follows. 1) Variability between the instrument devised by Kimura-Ishibashi and that devised by Fuse-Urakami. The tooth mobility by linguo-labial force (by drawing) measured by the Kimura-Ishibashi apparatus was larger than that measured by the Fuse-Urakami apparatus, but by labio-lingual force exserted on the tooth surface (by pushing) the tooth mobility was larger in Fuse-Uragami apparatus than in Kimura-Ishibashi apparatus. Besides this characteristic, it might be generally concluded that the Kimura-Ishibashi apparatus as compared to the Fuse-Uragami apparatus has certain theoretical weakness, though it is more handy in manipulating than is Fuse-Uragami apparatus. 2) The tooth mobility of left upper incisor in a 24 years old male subiect was studied in each case of loading at three different points of the labial surface, i. e., at the incisal margin, at the center of the surface and at the tooth neck. The tooth mobility was largest at the incisal margin, followed by at the center, and was smallest at the tooth neck. 3) The tooth mobility increased as the load applied was increased. 4) When the tooth was loaded in linguo-labial direction (drawn anteriorly), the mobility was larger than when the tooth was pushed in labio-lingual direction (posteriorly). 5) Of the mobilities of anterior teeth, that of lower incisor was the largest, followed by lower lateral incisor and that of lower cuspid was the smallest. There was no sex difference in this respect. 6) There was no remarkable difference in the tooth mobility between anterior teeth of same name on the right and left dental arch in subjects of both sexes, and in the maxilla as in the mandible. 7) Also there was no remarkable difference in the tooth mobility between the same named teeth in the maxilla as well as in the mandible. 8) The tooth mobility of anterior teeth in the female subjects

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A case of bilateral dwarf wisdom teeth in upper jaw was found in one of the craniums collected by the Anatomical Department of Kyushu Dental College Both teeth were comparatively long in length, but their crown were unusually small in bucco-lingual as well as in mesio-distal diameters, giving rise to bud-like shape, and were topped with three cusps. The cusps of the right tooth were differently arranged from those of normal teeth in that one cusp seated on the labial side and the other two cusps seated on the lingual side. The roots of both teeth were of slender conical shape with no branching. However the root of right tooth had a deep groove running longitudinally and set aside a little distally on the labial surface, whereby the root was imperfectly separated. The root of left tooth lacked groove and was purely single-rooted. The second molar was normal in the contour and the first molar was missing, making unable to compare the three molars as to their developmental stages. However in view of the apparent improbability that the degree of retrogrssion from the first to the second molar may be severe, such a sudden retrograde change and dwarfism shown in the third molar, especially in both sides of the dental arch, would be most interesting phenomenon. The wisdom teeth in lower jaw were normal in respect to their degree of retrogression.

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A maxillar right central incisor with an accessory root at labio-mesial side was found in a mass of teeth accumulated in our laboratory. Survey of literatures reveals that not rarely tendencies of root branching in mandibular incisors and accessory root in maxillar lateral incisors appearing at the point corresponding to cervicomarginal ridge on the lingual side of the root have been so far observed. However this instance of root branching or accessory root in the maxillar central incisor is rarely heard in the literatures, and it is most interesting to see that here the accessory root has developed on the labial side of the incisor. The tooth was generally normal in shape except that the accessory root was seen as a small protuberance. In the mesial side of the tooth a groove started from directly under the top of the mesial gingival line and proceeded aslant toward labial side of the tooth increasing the depth between main and accessory parts of the root and finally ending with complete branching of both. In the distal side of the accessory root no such long stretch of groove was found except weak depression present in the vicinity of the root branching. The root canal was not detected in the accessory root even by means of x-ray examination.

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The mandibular second milk molar tooth and the permanent fist molar are very similar in the morphology, and to the untrained eye they are liable to be mistaken one for another. The author measured various lengths of both teeth, and from this measurement the mean values of respective lengths and the indices thereof in both teeth were obtained. The morphological differences between both teeth were then statistically computed, and the results were summarized as follows. 1) In all the figures obtained from various parts of the crown the permanent first molar exceeded the second milk molar suggesting that the former was larger in size than the latter. 2) of all the values obtained that of bucco-lingual length was the largest, followed by that of longitudinal length of the crown in both teeth. 3) The ratio of the bucco-lingual to the mesio-distal length is smaller in the permanent first molar than in temporary second molar suggesting that the buccolingual length of crown is relatively well developed in the permanent first molar more than in the other. 4) Comparison of the ratio of the bucco-lingual to mesio-distal length in the cervical part of crowns of both teeth also show that the bucco-lingual length is relatively well developed in the permanent first molar more than in the other. 5) Comparison between the both teeth of the ratio of the bucco-lingual to mesio-distal length at the crown part to the same ratio at the cervical part showed that the ratio was larger in the permanent first molar than in the other suggesting that constriction at the neck of tooth was more severe in the second milk molar than in the permanent first molar. 6) The constriction, however, was more conspicuous in the bucco-lingual than in the mesio-distal length in the temporary second molar, and this relation was converse in the permanent first molar tooth.

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