220 THE MANAGEMENT AND DISEASES OF THE DOG. 



tion of parasitic diseases amongst animals) the part these 

 tapeworms are destined to play in the economy of life is not 

 merely remarkable, but altogether unique." 



The first he notices is the cucumerine tapeworm {Tania 

 cucumerind) : " It is a delicate and almost transparent tape- 

 worm, measuring from ten to twenty inches in length." 



This parasite is very common in English dogs, and, ac- 

 cording to Krabbe; infests 48 per cent of the dogs in Den- 

 mark, and 57 per cent of the dogs in Iceland. The animals 

 infect themselves in a singular manner. The joints of the 

 worm, having escaped /ler anum, readily crawl, as semi-inde- 

 pendent creatures, on the coat of the dog, chiefly on the back 

 and side. The eggs thus distributed are readily swallowed by 

 the louse of the dog {Tnkhodectes latus). 



In the body of the louse the six-hooked embryo, hitherto 

 contained in the egg of the tapeworm, escapes the shell and 

 becomes transformed into a minute cysticercus or louse-measle. 

 When the dog is irritated by the lice, it attacks, bites, and 

 frequently swallows the offending external parasite. In this 

 way the louse-measle is transferred to the dog's intestinal 

 canal, where, in course of time, it develops into the sexually 

 mature cucumerine tapeworm. 



Thus the mange-mite, or scab insect (as it is rather incor- 

 rectly termed), serves as the intermediary bearer of larval 

 tapeworm, and forms an essential factor in the production of 

 this particular species of cestode parasite. 



The Gid Tapeworm {Tania coenurus). This parasite. Dr. 

 Cobbold observes, probably does not occur in more than 5 per 

 cent of our dogs. In the native dogs of Iceland, according 

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



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

 tains 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 

 single hydatid, he swallows a colony of larvse, each of the 

 latter being destined to become transformed into a tapeworm 



