INTERNAL PARASITES. (ENTOZOA.) 2 19 



worm of the dog {Trkocephalus depressiusculus) inhabits the 

 caecum. The spiral flesh-worm {Trichina spiralis) ha.s fre- 

 quently been reared both in the intestines and muscles by 

 experiment. 



" The blood-infesting thread-worm of Grube and Delafond 

 {Filaria hczmaticd) is probably a distinct species ; and the 

 same may possibly be said of Gescheidt's small nematode 

 {Filaria trispinulosd), discovered in the eye. There are also 

 the small thread-worms {Filaria hepaticd) found by Mr. T. 

 Mather, V. S., in the liver-ducts and substance of the gland, 

 as well as in cysts within the walls of the intestines. 



" Lastly, there is another canine hsmatozoon, the males, 

 females, and embryos of which, according to Professor Leise- 

 ring, occur in the venous blood of certain parts of the body 

 of the dog {Hcematozoon subulatum)." 



Another, one of the most difficult to eradicate, and perhaps, 

 as Youatt observes, " the most injurious of the intestinal 

 worms," is the teenia, or tapeworm. With regard to this 

 species, Dr. Cobbold remarks : " Although the lumbricoid 

 worms of the dog constitute an important section of the ca- 

 nine parasites, the practical interest attaching to them is scarce- 

 ly so great as that which appertains to the tapeworms. If, 

 on the one hand, it be allowed that the canine cestodes are 

 not so numerous as the nematodes, it must, on the other hand, 

 be admitted that (as regards public health,* and the propaga- 



* In the fifth report of the medical officer of the Privy Council, Mr. 

 Gamgee observes : " There is no doubt that eggs of the tapeworm, devel- 

 oped from Cysticercus tenuicollis in the intestines of the dog, will produce 

 the hydatid in the mesentery and liver of human beings, as it does, accord- 

 ing to the experiments of Luschka, Leuckart, and others, in the organs of 

 the. domestic quadrupeds. 



" It is of the greatest importance that careful and extended inquiries 

 should be made as to the prevalence of these cysticerci in animals. It is 

 evident from the observations of KUchenmeister and others that many in- 

 dividuals of these species, forming extensive cystic tumors, are to be found 

 in pigs, and not unfrequently there has been a confusion between cysticerci 

 and echinococchi. Thus, in Ireland, the endemic cystic disease appears 

 to be due to both these hydatids." 



