THE KANSAS UNIVERSITY 

 SCIENCE BULLETIN. 



Vol. X, No. 7.] January, 1917. [ ^orxx^NT?. 



Larval Trematodes from Kansas Fresh-water Snails. 



BY EARL C. O'ROKE. 



Thesis submitted in partial fulfillment of the requirements for the degree of master of arts in the 

 Graduate School of the University of Kansas, 1916. 



Introduction. 



THIS study of larval trematodes was undertaken by the wi'iter 

 at the suggestion of Prof. Bennet M. Allen, in an attempt to 

 add to the knowledge of this interesting group of parasites. 



The snails used in the investigations were collected during the 

 summer and fall of 1915 in connection with the Kansas State Bio- 

 logical Survey, and studies were made of the beha\ior and habits 

 of the living cercarise before the specimens were preserved for 

 further morphological studies. 



Methods of Study. 



For convenience in transporting live snails, it was found de- 

 sirable to tie the specimens in cheesecloth bags of twenty-five 

 each, packing loosely in wet excelsior. 



In the laboratory the snails were isolated in indi\idual watch 

 glasses and kept covered with water. Normally the cercariae 

 emerged within two or three days. Some of the infected snails 

 were then preserved entire, and others were crushed for studies of 

 living sporocysts and redise. 



The fixatives used were a satui'ated corrosive sublimate solution 

 with one per cent glacial acetic acid, Zenker's fluid, and four per 

 cent formalin. The latter was discarded after trials proved the 

 superiority of the other fixatives. Corrosive sublimate was pref- 

 erable for free cercariae. 



Several different stains were used. Picrocarmine was excellent 

 for studies of the living cercariae. Specimens so stained could 



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 11— Sci. Bui. X. 



