Vol. L June, 1926 No. 6 



BIOLOGICAL BULLETIN 



FURTHER STUDIES ON THE LIFE HISTORY OF 

 CRASPEDACUSTA RYDERI, A FRESH- 

 WATER HYDROMEDUSAN. 



FERNANDUS PAYNE. 

 DEPARTMENT OF ZOOLOGY, INDIANA UNIVERSITY. 1 



In 1924 I published an account of a study of Craspedacusta. 

 This study included the morphology of the medusa and hydroid 

 and the development of hydroids and medusae from buds. The 

 life history was followed as completely as possible. For these 

 details, the reader is referred to my former paper (Payne, '24). 

 The story remained incomplete as all the medusae were females. 

 Since the publication of the paper I have continued to make 

 observations in Boss Lake, but have nothing new to add except 

 that medusae were not found during the summers of 1924 and 

 1925. The hydroids were still present in 1924, but no efforts 

 were made to find them in 1925. Since the hydroids were 

 present, at least in 1924, conditions must have been unfavorable 

 for medusae development. Males of Craspedacusta were reported 

 by Hargitt ('08) and Garman ('16 and '24). I have been anxious 

 to get the two sexes together and complete the life history. The 

 method which suggested itself was to find the hydroid of one of 

 these male strains and transplant it to Boss Lake, Elkhart. 

 The medusae live only a short time out of their native habitat, 

 so to transplant them would be impossible. The hydroid, on 

 the other hand, is very hardy. A change of water does not 

 affect it. The main requirement is a food supply. 



Through the kindness of Professor Garman, I learned where 

 the medusae had been most abundant in Benson Creek, Kentucky. 

 This gave me a good idea where to look for the hydroid. As 



1 Contribution No. 211. 

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