Natural History of Entozoa. 



197 



easily blown about by winds or carried by the legs of insects, 

 and thus, Dr. Cobbold teaches us, they may be dropped on our 

 food, and we may swallow them unawares. In the case of the 

 Tcenia echinococcus the dog acts as the preparatory host, and in 

 due time hands his dangerous guests over to his master — man. 

 This is a fertile source of death in Iceland. 



Dr. Cobbold advises scrupulous care and cleanliness in 

 regard to domestic animals. Neither dogs nor pigs should be 

 allowed to eat any filth they can pick up, and when animals are 

 infected they should be appropriately physicked and their 

 excreta burnt. It may be added that eating raw unwashed 

 vegetables is a very likely mode of conveying the germs of 

 dangerous parasites into the human frame. 



Fig. 22. — Sclerostoma syngamus, Diesing. — 1, Male and Female; nat. siez« 

 2, Upper part of same magnified, showing six-lobed circular lip of female, and the 

 male attached to her. 3, Lower end of the body of female, mag. 4, Ditto of 

 male, inverted, mag. 30 diam. 5, Mature egg, X 220 diam. 6, Egg, with con- 

 tained embryo, X 220 diam. 



" gapes," but 



Every keeper of poultry is acquainted with the 

 all do not know that this disorder is due to the unfortunate fowl 

 having to play the part of host to a parasitic worm. This 

 creature belongs to the Nematoda, or threadlike worms, and we 

 are able to give its portrait from Dr. Cobbold' s work. 



Its favourite residence is the trachea of common poultry, or 

 of certain wild birds. Dr. Cobbold considers that in the exit of 



