152 ANATOMV OF THE PORBEAGLE SHARK. 



thus of a mixed character is distributed to the stomach and intestines in 

 the usual manner. 



But we pass on now to the consideration of that all-important viscus, the 

 stomach, (st,) and looking first to that end of the organ directed towards 

 the oral aperture, we fail to recognise any line of demarcation, so generally 

 found in animals, at the point where the gullet (g,) terminates in the stomach, 

 constituting the cardiac orifice j in short we cannot define where the stomach 

 begins; the utility of such a patent condition of the oesophagus being evident, 

 inasmuch as the existence of a contracted aperture would not only prevent 

 the ready passage of large masses of food, but would also prevent the animal 

 from freeing itself of those indigestible portions of it which it is from time 

 to time necessitated to eject. 



If we next examine the opening, or pyloric orifice, (h,) by which the 

 digestible part of the food makes its escape into the intestines, we find here, 

 on the contrary, that the organ has suddenly contracted into a very narrow 

 tube, which is at once recognised as the duodenum, (i,) or small intestine. 

 Large masses of indigestible material are thus very efiectually prevented passing 

 in this latter direction, for if allowed to get into this part of the alimentary canal, 

 the great function of nutrition would be interfered with, moreover it is probable 

 that the existence of a peculiar valvular arrangement in the large intestine 

 would present an insuperable obstacle to its free exit. 



A most interesting structure, and one which presents a great diversity of 

 external configuration, is the spleen, (k, k, k.) In the present dissection we 

 find it divided into a multitude of unequal lobes, adhering together by folds 

 of the peritoneum with which it is invested, together forming an uninterrupted 

 chain of glands, and embracing lengthwise two-thirds of the circumference of 

 the stomach. The office this structure is destined to fulfil is not yet satisfactorily 

 ascertained, but numerous observations and experiments seem to prove that its 

 function is that of a blood-preparing organ. We next come to a gland whose 

 form is much more simple, and whose function is intimately connected with 

 assimilation; this is the pancreas, (1;) and here, like the spleen in man, it exists 

 simply as an elongated body slightly curved upon itself, but, unlike the spleen, 

 indicates a tendency to subdivision in the mesial line. The situation of this 

 organ might at first sight cause a doubt in the mind of the anthropotomist as to 

 its identity, but a little reflection will satisfy him that its position here is a neces- 

 sary result, consequent upon the shortening and abrogation of the small intestine. 



At this point of the alimentary canal we have three openings into the 

 colon or large intestine, (m.) We have the first formed by the termination 

 of the duodenum, (Ileo-colic valve;) the second formed by the entrance of 

 the pancreatic duct; and the third formed by that blind prolongation of 

 intestine known as the ^appendix vermiformis,' (n.) 



The colon, or great intestine, (m,) merits our particular attention; by its 

 aid the great function of nutrition is mainly carried on, and the mechanism 

 by which an enormous amount of material shall be absorbed into the system 



