68 EVOLUTION AND DISEASE. 
Sumatran rhinoceros. This animal, like all its kind, 
has a large cecum, the distal extremity of which cor- 
responds to the vermiform appendix, and derives its 
blood-supply from the terminal twigs of a long ileo- 
colic artery. The young animal to which these remarks 
refer was sent to the Zoological Gardens, London; at 
the end of a few weeks it became sickly, refused food, 
and finally died. At the autopsy it was discovered that 
the lower jaw was extensively diseased, and a large 
abscess had formed. This trouble offered satisfactory 
explanation of the loss of appetite and inability to take 
food. On examining the viscera, Mr. Frederick Treves 
discovered the actual cause of death to be ulceration 
and sloughing of the extremity of the cecum. In this 
rhinoceros we have a similar condition of things to the 
gangrene of the toes after typhoid fever, for the vital 
powers being reduced by the trouble in the jaw, and the 
inability to take sufficient food, those parts at the end 
of the circulatory system suffered first, and the structure 
most ready to succumb was the distal end of the caecum. 
This case is very suggestive, because it teaches how, in 
the process of evolution, so far as individual parts are 
concerned, a limit is imposed upon the size attainable 
by organs, and indicates the danger to which animals 
are exposed in which particular vital organs attain in- 
ordinate proportions. For instance, imagine two animals ; 
living under similar conditions and upon the same kind 
of food, but one has a moderate czecum, the other an 
inordinately large one. Should a time of scarcity of | 
accident prevent such animals obtaining a proper 
supply of nutriment, the one with an average caecum ; 
(ceteris paribus) has the better chance of survival. 
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