la. 



pratawcrioH. 



Although many different species of adult 

 been recorded, nowhere in the literature do we find the des- 

 cription of all the stages of their life cycle* In 1909, Luh 

 (1909, p. 65} clearly states that up to that time the life 

 cycle was insufficiently known and that with a certainty no 

 cercaria had been identified as belonging to a definite -adult 

 echinostome. The nearest approach to finding all the stages 

 of the life cycle was made by Hi coll (1906, 1906a) and 

 Lebour (1908) in their work on IS oh i no 8 to mum secundum Hi coll* 

 However, the 3* workers definitely state that no stage before 

 the redia with oercariae inside were seen* Since that time 

 neither in Europe nor America h^ve all the missing stages 

 been traced. This lick of information is due mostly to the 

 complex life cycle* 'Ihe chief difficulties involved are 

 those of oo nneoting exactly, by experimental feeding, the 

 encysted agamodistome with the adult eohinostome md of 

 finding the exact species or genus cf snail into which the 



miracidium will enter. 



. 



Knowledge concerning the entire excretory ays tern of any 

 stage of the life cycle of an echinostome is even less oomple 

 than that of the life history. This lack of knowledge is due 

 largely to wrong methods of study which formerly consisted 

 of using only preserved specimens* 



At the suggestion of Professor W. W, Cort, the writer 

 undertook in August 1917 to work out the excretory system 

 of an echinostome oercaria which later proved to belong to 

 Jch ino s to ma re vo lut am (Jroelich). After tracing the 



