PARASITIC DISEASES, 337 



ment of an important organ. We have instances of this in 

 the epileptic seizures or other convulsions of children and of 

 young animals suffering from intestinal parasites. 



The parasites, I have to refer to, belong to the three orders of 

 cystocestoid or tapeworms, nematoid or round worms, and tre- 

 madote or sucking worms. Of some of these, particularly of 

 tapeworms and sucking worms, it is characteristic that in their 

 development they pass through a non-sexual stage, during 

 which they may infest different animals from those in which 

 they dwell during the sexual and reproductive stage of their 

 existence. And thus the same parasite may kill more than 

 one animal. Human beings derive most of their parasites 

 from the domestic quadrupeds. Leuckart says, " The chief 

 result of our observations on the life history of the helmin- 

 thoid animals is to the effect that by far the greater number 

 of these creatures live in their various conditions in different 

 animals. Applying this conclusion to the human parasites, 

 we find that in all probability the greatest part of our entozoa 

 are derived from animals. It is the animals with which we 

 come most in contact, viz., our domestic animals, and espe- 

 cially those we eat, that communicate parasites to us . . . 

 "The justness of this conclusion is demonstrated without 

 doubt by observations and experiments. The domestic ani- 

 mals furnish us, in fact, with the greater number of parasites, 

 but under different circumstances. The parasites which we 

 derive from the animals we eat, such as the tapeworm and 

 the trichina, belong to the developed intestinal worms. We 

 acquire them in their young state, the tapeworm as hydatids, 

 and the trichina as an encysted muscle worm, and both from 

 pigs, which are the animals that mostly give us the eggs and 

 embryos of their entozoa, which then develope in our bodies 

 in their early condition. Of the encysted parasites the dog, 

 above all others, supplies us with germs. It is it that 

 VOL. ii. 3 Q 



