84 PROPHYLACTIC MEASURES. 



contact either with the flock or their food. This supervision of 

 the dog will be continually necessary, since although, according 

 to my experience, the period of the parasite's existence is confined 

 to only a few weeks, the opportunity for its immigration into the 

 dog may frequently occur again. For the rest, I have pleasure 

 in thinking that I have pointed out the true cause of the origin 

 of the Coenurus cerebralis, and hinted to the sheep-breeders in 

 what way the worm creeps into their flocks ; and I now leave it 

 to intelligent proprietors to employ those means which are best 

 fitted for the purpose of arresting the enemy, according to the 

 locality, the style of farming, or to the condition of the animals. 

 Having furnished a statement of the natural history of the 

 Coenurus cerebralis, I must leave it to experience to show if there 

 are really means of preserving a flock of sheep from this cestoid 

 parasite, and if so, what kind of means. 



The Tcenia serrata of the dog, whose presence in the sheep-dog 

 is most particularly to be guarded against, is easily distinguish- 

 able from the other, harmless, tape-worm of the same animal, 



rig. 36. 



the Tcenia cucumerina ; the first having its developed joints always 

 white, and of a quadrangular or oblong shape, with only a single 

 irregular marginal sexual aperture, varying in its position on each, 

 whilst the developed joints of the Tcenia cucumerina are elliptical 



Fig. 36. Tcenia cucumerina, from the intestines of a dog, with perfectly developed 

 joints, natural size. 



