ANIMAL PARASITES. i33 



the supra-pubic region, irritability of the bladder, and 

 hematuria; in the latter, straining, tenesmus, and the 

 passage of blood and mucus. Ova are found in either 

 discharge, and the diagnosis rests upon their discovery. 

 Haemic distomiasis is a very important disease, as its 

 prevalence in many countries attests. Since communi- 

 cation with the East has become closer, a larger number 

 of imported cases have been reported. Dr. Stiles is 

 of the opinion that the United States will suffer from 

 importation of parasites by troops returning from foreign 

 service and by travelers. The same author leans to 

 the belief that a snail acts as intermediate host for the 

 h^matobium. If this be true, before the disease can 

 become endemic in the United States depends upon 

 *' whether there exist in the United States species of 

 snails which can serve as intermediate hosts, and 

 whether these snails actually become infected by persons 

 harboring the parasite." Furthermore, if snails act 

 as intermediate hosts, then "cases of infection are 

 more likely to occur in rural districts than in cities, 

 and country physicians will be more likely to encounter 



them'' (Stiles). 



CESTODES. 



Cestodes or tape-worms are flat, segmented, ribbon- 

 like worms which have their habitat in the small intes- 

 tines. They are characterized by a complete absence 

 of a mouth or digestive tract, and nourishment is 

 maintained entirely by absorption of nutrient material 



