DISEASES PBODUCED BY CYSTICA. 83 



If we fix our attention upon sheep, which are unfortunately 

 too often exposed to the dangerous attacks of the Camurus 

 cerebralis, we shall find that very frequently when a flock of 

 sheep is attacked by the Coenurus cerebralis, it is the sheep-dog 

 who has guarded them year after year who is answerable for 

 the mischief; in this case the shepherd's dog is infested by the 

 Tcenia serrata, whose young, after being passed by the dog in the 

 neighbourhood of the flock, are easily caught up and swallowed 

 by one sheep or another without being observed. The surest 

 means, then, of keeping off the Coenurus cerebralis from a flock 

 of sheep would be to do away with the sheep-dog. To this, 

 however, the sheep-breeders would hardly agree, since the ser- 

 vices of a first-rate sheep-dog are not to be easily replaced by 

 any other kind of help. But that the sheep-dog is really con- 

 cerned in the devastations which the Ccenurus cerebralis makes 

 in a flock is borne out by the fact that those sheep-flocks which, 

 in the true sense of the word, are stall-fed, and consequently 

 unattended by a dog, are never, or at least very rarely, troubled 

 with the Camurus cerebralis. Those sheep-breeders who are 

 disinclined to give up keeping dogs to guard their flocks, could 

 urge as an objection that their dismissal would afford no sure 

 guarantee for keeping off the parasite, inasmuch as the pastures 

 where the sheep feed might become contaminated by the young 

 of the Tcenia serrata through other dogs, such as hounds and 

 mastiffs; perhaps, indeed, even by wolves, foxes, or martens, and 

 other animals of prey (see page 76). 



Since, also, I have pointed out the identity of the Tcenia 

 solium of the human subject with the Tcenia serrata of the dog 

 (see page 68), there appear to be so many possible ways open 

 for the dispersion of the cestoid embryos and their development 

 into the Coenurus cerebralis, that it needs the utmost care to 

 discover means of always cutting off the approaches by which 

 these dangerous parasites effect an immigration into the sheep. 



If, after these objections, which I have myself raised, I am 

 the less inclined to think that the doing away with the sheep-dog 

 would be an absolute preventive against the Ccenurus cerebralis, 

 yet, I at least believe that, as a rule, and as a wise pre- 

 caution, it might be recommended to those sheep- owners 

 who employ dogs in the care of their flocks, to exercise a 

 watch over them. If the dog be troubled with the T&nia 

 serrata, the worm should be expelled before the animal comes in 



