The life histor.y of Diplocliscus temporatus Stafford. 615 



Die Weiterentwicklung- des Wurmes erfolgt, wenigstens im ersten 

 Frühjahr, ziemlich langsam." 



Lang states that, in some instances at least, the transfer of 

 the encysted cercariae of this form comes about through the fact 

 that the adult cercariae encyst on the skin of the Batrachians, and 

 when this is shed, the worms are taken into the digestive tract 

 along with the old cuticle and then find their way to the cloaca, 

 where the remainder of their development takes place. 



In the light of the observations recorded above, it seems im- 

 probable, to say the least, that the transfer of the encysted cercariae 

 of BipJodiscus temporatus to the vertebrate host takes place in a 

 similar manner. In both the bodies of water where the infected 

 snails were found in abundance there were very few water plants 

 of any kind floating on the surface. The banks, on the other hand, 

 Avere covered with rocks which would serve as a suitable place for 

 the attachment of the cercariae when about to encyst. On the basis 

 of the observations made in the laboratory, it would seem that the 

 only way in which the cysts would be likely to reach the bottom 

 would be for them to be formed on water plants, which on their 

 decay would set the cysts free in the water. 



Granting- that the cercariae become encysted on the banks, or 

 on hard bodies floating in the water, there are two possibilities for 

 their transfer to the digestive tract of a Batrachian where they 

 could complete their development. They might be taken up from 

 their place of attachment by a tadpole while it was browsing over 

 the rocks or the vegetation along the banks. In this event it would 

 at once be placed in its natural environment where the further 

 development might go on to its completion. In tadpoles of Rana 

 cateshiana, which may require one year to reach the adult condition, 

 the worms might become sexually mature and give ott" their sexual 

 products before the time for the metamorphosis of the tadpole. 



In those tadpoles which undergo their metamorphosis during 

 the same season in which the eggs from which they develop were 

 laid, the fundamental changes \mdergone by the digestive tract of 

 the tadpole might cause the voiding of the worms along with the 

 old lining of the gut. 



The other alternative would be that the cysts would be taken 

 up from their attachment by some animal which could not serve 

 for the final host, in some of whose tissues the worm would become 

 again encysted. This intermediate host, provided it was included 



