ON THE OCCURRENCE OF A PARASITE OF THE PIKE 

 IN EUROPE, MYXIDIUM LIEBERKUHNI BUTSCHLI, 

 IN THE PIKE ON THE AMERICAN CONTINENT 

 AND ITS SIGNIFICANCE. 



JAMES W. MAYOR, 

 UNIVERSITY OF WISCONSIN. 



CONTENTS. 



PAGE 



1. Introduction 373 



2. Findings in Fresh Preparations 373 



3. Findings in Stained Preparations 375 



4. On the Significance of the Occurrence of Myxidium Lieberkiihni in Both 



Europe and America 375 



5. Papers Cited 376 



6. Explanation of Plate 378 



i. INTRODUCTION. 



In a previous paper (Mavor, 19166) the author has recorded 

 the occurrence of what he believed to be Myxidium lieberkuhni 

 Biitschli in the urinary bladder of the Pike, Lucius lucius L. 

 from the Georgian Bay. The parasite was then identified on 

 the basis of the structure of the plasmodial stage, and two spores 

 which were all the author was able to find at that season of the 

 year, July. 



While searching for the parasite in a pike caught in Lake 

 Mendota, Wisconsin, on May 5, 1916, he was able to find abun- 

 dant spores and stages in the sporogenesis. This material forms 

 the basis of the present paper. 



2. FINDINGS IN FRESH PREPARATIONS. 



The plasmodial stage was very abundant in the urinary 

 bladder. When this was examined the urine had been evacuated 

 and what little remained upon being withdrawn with a pipette 

 held close to the inner surface of the bladder was filled with 

 plasmodia. These with the exception of a few larger forms 

 were almost uniformly spherical in shape and ranged from 10 ju 

 to 80 IJL in diameter. Many of these show areas on their surfaces 



373 



