374 TRANSLATIONS AND SELECTED ARTICLES. 



of the helminth, and the shepherd's dog incurs the grave suspicion of 

 infecting the flock committed to his charge. 



"Nevertheless, however great may he the complications attending a 

 migration of this kind from one animal to another, and the subse- 

 quent journey through its tissues, if it is shown actually to take place, 

 however mysterious the proceeding may appear, logically we are bound 

 to admit its reality. But it is precisely at this point that we meet 

 with, we will not say insurmountable, but with, at any rate, enormous 

 difficulties. Let us see what these are. 



" The Gaenurus cerebralis, according to V. Siebold, Van Beueden, 

 and other naturalists, would be the larva of Taenia serrata. But, 

 on the other hand, this Taenia serrata, according to Kiichenmeister, 

 Van Bengden, Baillet, and V. Siebold himself, would appear to be the 

 product of Cysticercus pisiformis, or of Oj/sticerus cellulosae, and 

 C. tenuicollis, according to what V. Siebold further says. 

 - " Here we find ourselves in the utmost embarrassment. It must 

 be allowed, however, that zoologists have exhibited great ingenuity in 

 this matter, if they have not been very exact. Immediately a Taenia 

 is met with in any carnivorous animal whatever, the evil is at once 

 imputed to his victim. The cat derives its worms from the rats and 

 mice it devours ; the wolf and the dog find theirs in the rabbits and 

 sheep ; man is indebted to the pig. But a scrupulous examination of 

 the facts excites some doubts with respect to all this. It may be 

 asked, for instance, how is it that the sheep, which does not eat the 

 flesh of any animal, sometimes has its intestine filled with such a 

 multitude of Taeniae as to have it completely obstructed by them ? 

 In an epizootic malady, which carried off many sheep in the neigh- 

 bourhood of Rouen, in 1852, this was the case in almost every in- 

 stance. If the tapeworms find themselves so well off in the intestine, 

 why should the larva of some of them quit that locality, and be 

 obliged to take a compulsory journey to the brain ? 



" The importance of this question, as regards agriculture, has not 

 escaped M. Le Roy, Prefet of the Seine-Inferieure ; and by him we 

 have been instigated to experiment on a large scale on this grave 

 subject. 



" Several causes have evidently contributed to throw a degree of 

 uncertainty on the results of experiments of this kind. In the first 

 place, must be placed the natural frequency of the Entozoa which are 

 employed upon the animals to which we profess to communicate them. 



