Internal Parasites, 



227 



The Gid Tapeworm {Tcenia coenurus). This parasite 

 Dr. Cobbold observes, probably does not occur in more, 

 than 5 per cent, of our dogs. In the native dogs of Ice- 

 land, according to Dr. Krabbe, it occurs in 18 per cent. 



In order, says Dr. Cobbold, to understand how the dog 

 obtains this tapeworm, it must be observed that gid- 

 hydatids, or canuri, each represent a sort of colony of 

 larval parasites. When, therefore, the dog eats a sheep's 

 brain containing a singie hydatid, he swallows a colony 

 of larvae, each of the latter being destined to become 

 transformed into a tapeworm in the bowel. Thus Fig. 26 

 represents two hydatids, one being viewed from without, 

 and the other from within. At A the young tapeworm 

 heads are seen projecting from the exterior surface of the 

 hydatid ; whilst at B they are seen retracted within the 

 interior of the bladder- worm. There may be from three 

 to five hundred of these heads projecting from the surface 

 of a single gid -hydatid. 



FIG. 26. 

 larvjE of the gid tapeworm, (newman.) 



If a small fragment of the gid-hydatid with its charac- 

 teristic processes be magnified about eighty diameters, all 

 the more essential structures will be brought into view. 

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