| OCR Text |
Show 1900.] SOFT ANATOMY OF THE MUSK-OX. 153 sixth are situated more centrally and covered by the other coils. The seventh lies between the second and first coil, but the eighth is still more peripheric. At 8 in the figure it is shown to make a long loop (y), and then having returned upon itself it passes out in the periphery of the mesentery near the short convolutions of the small intestine, to which it is fixed with a narrow (about 3 cm.) mesentery. Owing to this narrowness of the mesentery, the large intestine is forced to make some undulations, although not so many or so deep as the small intestine. When the large intestine has come to the pancreas region it leaves the mesentery of the jejunum, and becomes connected with the first part of the colon (the first coil) iu a direction opposite to that of the latter towards the right side, and, returning upon itself, makes a loop, both ends of which are closely connected at x in the figure. Then it passes backward into the rectum. With regard to the figure, it is to be observed that the intestine is laid out and the coils of the spiral are pulled apart a little; the upper parts of the spiral being to the right and the lower parts to the left, so as to make all the coils at least partly visible. W h e n comparing the large intestine of Ovibos with that of other Ruminants, it becomes evident that the former is more developed and thrown into more coils (4 centripetal and 4 centrifugal). If the spiral coils are counted in the same manner as above, we find that the colon of Capreolus makes 2\ centripetal spiral coils and 2\ retrograde or centrifugal ones. The same organ in Capra and Ovis makes 3 centripetal and 3 retrograde spiral coils. In Bos, as a rule, only 2 centripetal and 2 centrifugal coils (sometimes only 1^ of each) can be discerned. The situation of the last centrifugal coil is different in Ovis and Capra on the one side, and Bos on the other, since in the two former it lies peripherally quite close to the coils of the small intestine. The same is also the case in Ovibos, as already stated; but although this characteristic separates Ovibos from Bos, it has no value for uniting Ovibos with the Ovine group, because the same condition is also found in other Ruminants, as, for instance, Capreolus, in which the mesentery between the small and the large intestine is 1|-2| cm. It is therefore probable that this is an ancient character retained by most Ruminants except the Bovine group. The situation of the colon gives therefore no reason for uniting Ovibos with Ovis and Capra in a subfamily of Cavicornia. O n the contrary, the greater development of the spiral coils indicates that the Musk-ox is differentiated with regard to this organ from the others. The same result may be obtained by comparing the measurements of the different parts of the intestine with each other, and comparing this relation with the correspondig one in other species. The length of the different parts of the intestine of the Musk-ox measured in a preserved state, but still adherent to the mesentery, is as follows:- Small intestine from pylorus to caecum 26 m. 70 cm. Ca?cum 70 cm. Large intestine 12 m. 40 cm. |
