高原産鼠(Rattus屬)の骨の相對成長に就て

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Applying the formula y=bx^<a>, the relative growth of bones of the head, extremities including the girdle, and also of the breast against the basilar length was investigated on the rats caught at Sugadaira situated on a high plateaux 1300〜1400 in above sea level and having nearly 100 farm houses. The rats were of 2 kinds, namely R. norvegicus and R. rattus rattus. As the specimens of R. rattus rattus were few, the present report will mostly deal with the results obtained in the case of R. norvegicus. It must however, be said that very little differences could be detected between the results obtained in these 2 species. Equilibrium constant (α) and its probable error as well as the initial growth index (b) were computed by the least square method (Tabnle 1). The result may briefly be summarized as follows: 1. As far as the measurements chiefly of adult bones are concerned, the growth of the bones can be represented by a straight line. The breadth of the coxal, parietal, frontal bones as well as the length of the lower diastema of the male and also the length of the lower diastema of the female being exceptions to the above rule, seem to have 2 stages or periods in their development and must be accordingly divided into 2 lines with a break occurring somewhere near 30 mm in basilar length, the lower diastema 1. of the male being an exception because in this the break takes still later. With the exception of a few the value of α is always smaller than 1 (negative allometry) and it is markedly smaller than 1 in many bones in the skull. In the bone other than the skull, on the other hand, the value of α is markedly greater than 1. This is especially true in the case of the femur, coxal l., scapula, and the 1st and 4th sternebra of the male and also the coxal br. and the 4th sternebra of the female. In all these cases α value reaches nearly to 2 or even more. 2. The growth of the bones in the cranium in breadth exceeds that in length so much that the cranium itself takes on gradually elongated shape. The growth in height, however, of the cranium seems to lie between those in length and width. The value of α for both the upper and the lower molar series 1. is so small as to indicate no sign of growth. The growth of the bones on the dorsal surface of the cranium show in their 1. as well as br. a simple growth gradient. The growth, in short, is marked at both the anterior as well as posterior parts, but in breadth the posterior part decidedly exceeds all other parts (Fig. 3). 3. In the fore limbs the value of α in any single bone is larger than 1, showing the existence of a simple gradient with the value of α decreasing proximo-distally. 4. Generally speaking, the value of α in the hind limbs is much larger than in the fore limbs, showing nearly the same gradient as in the case of the fore limbs, but in the males the growth center seems to lie in the femur if the breadth is taken at the coxal. 5. In the sternum the value of α is still larger, showing a double growth gradient with the center in the fourth sternebra (Fig. 4)
社団法人日本動物学会の論文
1942-03-15

高原産鼠(Rattus屬)の骨の相對成長に就て

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