154 NATUilAL iHJiOLOar. 



a man. In truth, it must in both have been formed, not by 

 action, but in direct opposition to action and to pressure ; 

 but the opposition which would arise from pressure is greater 

 in the upright trunk than in any other. That theory, there- 

 fore, is pointedly contradicted by . the example before us 

 The structure is found where its generation, according to 

 the method by which the theorist would have it generated, 

 is the most difficult ; but observe, it is found where its effect 

 is most useful. 



The different length of the intestines in carnivorous and 

 herbivorous animals has been noticed on a former occasion. 

 The shortest, I believe, is that of some birds of j)rey, in which 

 the intestinal canal is little more than a straight passage 

 from the mouth to the vent. The longest is in the deer 

 kind. The intestines of a Canadian stag, four feet high, 

 measured ninety-six feet.^ The intestines of a sheep, un- 

 ravelled, measured thirty times the length of the body. The 

 intestines of a wild cat are only three tim^s the length of the 

 body. Universally, where the substance upon which the 

 animal feeds is of slow concoction, or yields its chyle with 

 more difficulty, there the passage is circuitous and dilatory, 

 that time and space may be allowed for the change and the 

 absorjDtion which are necessary. Where the food is soon 

 dissolved, or already half assimilated, an unnecessary or per' 

 haps hurtful detention is avoided, by giving to it a shortei 

 and a readier route. 



V. In comparing the hone?, of different animals, we are 

 struck, in the bones of birds, with a i:)ropi'iety which could 

 only proceed from the wisdom of an intelligent and design- 

 ing Creator. In the bones of an animal which is to fly, the 

 two qualities required are strength and lightness. AVherein, 

 therefore, do the bones of birds — I speak of the cylindrical 

 bones — differ in these respects from the bones of quadru- 

 peds ? In three properties : first, their cavities are much 

 larger in proportion to the weight of the bone, than in those 

 ^ Mem. Acad. Paris, 1701, p. 170. 



