IN THE BODIES OF ANIMALS.' 395 



these animals a singular and beautiful adaptation of structure 

 and function to the peculiar circumstances of their existence, 

 and they present us with another instance of the fostering care 

 which nature displays in the preservation of her oifspring. 

 The proportion between males and females (that of the latter 

 being by far the greatest) ; the immense number of embryones 

 and eggs generated, by which arrangement the preservation 

 and maturation of some, at least, is preserved ; the extreme 

 delicacy of structure in these, of itself an unanswerable objec- 

 tion to their being transported into other situations ; and, 

 lastly, their fugacious vitality, (the parents dying imme- 

 diately on the exclusion of their young) ; are facts, all of 

 which conspire to form the opinion that they are peculiar 

 animals. 



A careful examination of the facts bearing on this question 

 has brought us to the conclusion that neither the eggs of 

 worms, nor the worms themselves, enter the animal body by 

 any of the mucous cavities. Under this conviction, therefore, 

 I thought it very desirable to ascertain the earliest period in the 

 life of an animal at which worms exist, and with this view 

 instituted the following experiment. Having a pregnant cat 

 at hand, I determined upon making the experiment upon her 

 kittens. I had two motives in selecting cats as the sub- 

 jects of experiment: 1st, 'I'hat I have invariably found worms 

 in adult cats at various ages ; viz. Ascaris mystax in the 

 stomach and small intestines, and Tania cuneiceps in the 

 latter situation. 2dly, That the kittens would have been 

 killed in the usual course of events, and therefore that I was 

 not laying myself open to the charge of wantonly wasting life. 

 Well, her accouchement brought five young. The first I killed 

 instantly, but on examination found nothing but mucus and 

 meconium. At the end of the third day I examined the second, 

 and discovered two Ascarides in the stomach, and several pieces 

 of small Tcenicem the small intestines. At the expiration of the 

 fifth day the third was examined, but to no purpose ; for, 

 although I explored the whole intestinal part with a lens, 

 no trace of a worm was present. At the end of the tenth day 

 the alimentary canal of the fourth was exposed. Three 

 Ascarides in the stomach, one in the duodenum, and two 

 perfect Tccnia, besides pieces, were brought to light. 



I deferred the examination of the fifth till the fifteenth day, 



