PROF. OWEN ON THE ANATOMY OF THE INDIAN RHINOCEROS. 43 



fibres in the rectum and those of the external sphincter was well-marked, the latter pre- 

 senting the striated character of true voluntary muscles. 



The herbivorous Mammalia differ from the carnivorous more in the character of their 

 large intestines than of their small intestines. The less putrefactive nature of their food 

 renders it susceptible of a longer retention in the body ; and the receptacular and sac- 

 cular character of the large intestines seems especially designed to retard the course of 

 the aUmentary substances. An observation made by the celebrated Surgeon Dupuytren, 

 throws light upon the final purpose of this detention of the food of the Herbivora : he 

 noticed in a patient who had an artificial anus near the end of the small intestines, 

 that the vegetable parts of the food thence ejected were undigested. Dr. Beaumont 

 also observed that the vegetable substances underwent much less change than the 

 animal substances in the stomach of the man (Alexis) with the fistulous opening into 

 the stomach. That organ in the artiodactyles (Peccari, Hippopotamus, and Ruminants) 

 is rendered specially complex for overcoming the difficulty, and the caecum and colon 

 are comparatively small : but in the perissodactyles (Horse, Tapir, Rhinoceros) the 

 more simple stomach is compensated by the increased capacity and complexity of 

 the large intestines. The subdivided stomach in the Sloths is in some respects, as 

 e. g. the glandular appendage, and vascular secerning surface of the paunch, more com- 

 plex than that of Ruminants : and here accordingly we find the caecum absent and the 

 colon undefined. These facts should be kept in mind by the Physiologist when he draws 

 from Comparative Anatomy in support of inferences as to the special function of the 

 caecum in completing the digestion of vegetable food. The Dormouse and other hyber- 

 nating Rodents are far from being the sole exceptions to the presence of a proportionally 

 large ctecum in the Herbivora : a large cscum is rather the exception than the rule in the 

 vegetable feeders. It is only found in those Herbivora, in which, through the necessity 

 of a correlation with other circumstances than that of the nature of the food, the stomach 

 retains the simple form and moderate size of that of the carnivorous or mixed feeding 

 mammals. Comparative Anatomy significantly warns us against ascribing a special or 

 exclusive importance to any particular dilatation of the alimentary canal. It plainly 

 demonstrates that neither a complex stomach nor a large caecum are essential to the 

 digestion of vegetable food : but it teaches that a capacious and complex alimentary 

 canal is essential for that purpose, at least in the Mammalia. Either a highly-deve- 

 loped and concentrated glandular apparatus must be added to the stomach, as in the 

 Dormouse, Wombat and Beaver ; or the stomach must be amplified, subdivided or sac- 

 culated, as in the Ruminants and herbivorous Marsupials ; or both complexities must be 

 combined, as in the Sloths, Dugongs and Manatees ; or, if a simple condition of stomach 

 is retained, it must be compensated by a large sacculated colon and caecum. 



Digestive glands.— The liver presented the dark colour noticed by Mr. Thomas in his 

 dissection of the Rhinoceros. In the female specimen which I examined, its texture 

 was as firm as in the Horse, and its weight was 21 lbs. avoirdupois. In the older and 



