The life history of Diplodiscus teraporatus Stafford. 613 



by the larg'e posterior sucker. The anterior part of tlie body Avas 

 in almost constant motion. 



Others of the tadpoles used in this experiment died from time 

 to time and were examined for the presence of worms. The result 

 of the examination was identical in every instance. A greater or 

 less number of worms, ranging from ten to thirty one, was found 

 in tlie posterior part of the intestine. In no case were any of the 

 worms, or any other recognizable parasites, found in any of the 

 other organs of the tadpoles. 



The intestines of two of the tadpoles at the time of their death 

 contained worms still within the cyst. Among the others, individuals 

 of different ages could be recognized so it was definitel}^ etablished 

 that the tadpoles could serve as the host for the sexually mature 

 worms. 



Since it seemed probable from the number of worms found in 

 each of the dead tadpoles that they had in many instances been 

 the direct cause of the death of the host, some larger tadpoles were 

 secured for further experiments. These were put into the jars 

 containing encysted cercariae; but after they had remained there 

 for a few days they were transferred to a jar in which there had 

 been no snails. A tadpole from this jar was killed each week to 

 note the development of the parasites. The conditions of the 

 environment proved unfavorable for the tadpoles, and the last one 

 of them died on Jan. 19th. 1909, after having been infected with 

 the Diplodiscus for about nine weeks. The worms which were taken 

 from the intestines of this tadpole had fully developed sexual organs, 

 bnt, so far as could be determined from the examination of the jar. 

 no eggs had been laid, or at least no embryos developed. 



While the above described experiments were in progress, 

 attempts were made to infect other animals. The intestines from 

 infected tadpoles were fed to a turtle {Chrijsemys picta), to toads 

 {Bufo lentigunosus), and to frogs {Rana virescens). Two weeks after 

 the third feeding of the turtle it was killed and the intestines 

 examined for parasites. The only contents of the digestive tract 

 was a dark mass in the cloaca. On microscopic examination this 

 mass was shown to be made up of the remains of the tadpole 

 intestines; but no trace could be found of the worms, twenty in 

 all, which had been fed with the tadpole intestines. 



The frogs, five in number, which were used in this experiment, 

 were secured from a spring which was at least one mile from the 



