78 ASSIMILATION IN CARNIVORA. 



XVI. If we now compare the capacity for increase 

 of mass, the assimilative power in the grarninivora and 

 carnivora, the commonest observations indicate a very 

 marked difference. 



A spider, which sucks with extreme voracity the 

 blood of the first fly, is not disturbed or excited by a 

 second or third. A cat will eat the first, and perhaps 

 the second mouse presented to her, but even if she 

 kills a third, she does not devour it. Exactly similar 

 observations have been made in regard to lions and 

 tigers, which only devour their prey when urged by 

 hunger. Carnivorous animals, indeed, require less food 

 for their mere support, because their skin is destitute of 

 perspiratory pores, and because they consequently lose, 

 for equal bulks, much less heat than graminivorous ani- 

 mals, which are compelled to restore the lost heat by 

 means of food adapted for respiration. 



How different is the energy and intensity of vegeta- 

 tive life in the grarninivora. A cow, or a sheep, in 

 the meadow, eats, almost without interruption, as long 

 as the sun is above the horizon. Their system possesses 

 the power of converting into organized tissues all the 

 food they devour beyond the quantity required for mere- 

 ly supplying the waste of their bodies. 



All the excess of blood produced is converted into 

 cellular and muscular tissue ; the graminivorous animal 

 becomes fleshy and plump, while the flesh of the carniv- 

 orous animal is always tough and sinewy. 



If we consider the case of a stag, a roe-deer, or a 

 hare, animals which consume the same food as cattle 



