452 SCIENCE PROGRESS. 



With regard to the members of the two orders mentioned 

 in the table, certain points in their geographical distribu- 

 tion are of interest. Tcenia marginata, the largest Taenia 

 which inhabits the dog, Dipylidiiim caninum and Ascaris 

 mystax occur in all the widely distributed places mentioned. 

 T. serrata is absent from Iceland, that home of dog-parasites, 

 where ioo per cent, of the dogs are infested with some form 

 or other of Entozoa. T. ccznuriis, whose larvel form infests 

 the brains and more rarely the spinal marrow of sheep, is at 

 present unknown in America, and is not mentioned in 

 Thomas' lists from S. Australia and Victoria. The loss 

 annually caused by the " Gid "or " Staggers," as the disease 

 caused by its presence is called, has been estimated at 

 1,000,000 sheep in France and 35 per cent, of all the flocks in 

 England, if the season be a bad one. Naturally it is com- 

 monest in sheep-dogs and comparatively rare in town-bred 

 animals. T. serialis is also rare, in fact in some recent lists 

 the name of its host is preceded by a query. It, however, 

 undoubtedly occurs in the dog though only recorded on our 

 list from Lincoln. D. cajiinum, as mentioned above, occurs 

 both in the cat and the dog. 



The really important parasite, from a merely human 

 point of view, is the Echinococcus polymorphus, "the most 

 insidious and dangerous parasite which inhabits the human 

 system ". In Iceland and in Australia it infests about 30 

 per cent, of the dogs examined. And when we are re- 

 minded that in the former island there are about twenty- 

 eight dogs to every hundred inhabitants, and that during 

 the long winter days men and beasts live together in the 

 same huts without sanitary precautions, it is not surprising 

 to learn that one in every forty-three individuals suffers 

 from echinococcosis. Happily this form is absent from 

 America, though Sommer has recorded 100 cases of the 

 disease from the medical literature of the last fifty years. 

 Probably the sufferers brought the parasite with them into 

 the new country. 



The result of the Nebraska research shows that on the 

 whole there is a large percentage of harmless parasites in 

 the dogs of that State and an excessive rarity — speaking 



