GERM CELLS OF COELENTERATES 611 



cells. For, medusae were found with the sexual products only, 

 others possessed buds and no sexual products, and still others 

 showed buds in abundance and sexual products forming or 

 actinulae developed. Perhaps nearly one half of. the specimens 

 had both buds and sexual products present. The sexual and 

 asexual reproductive processes of the medusae may thus occur 

 simultaneously, or the buds may develop and be liberated before 

 the sexual products form. Since all these conditions are found 

 in medusae taken at the same time and from the same place, 

 and since there is no correlation which can be observed between 

 the size of the medusae and the presence of buds, it is probable 

 that budding is not a rhythmic or periodic process. Buds have 

 been found on specimens in the autumn (C. W. Hargitt '04), 

 and Agassiz ('62) found two generations of buds present before 

 the medusa was liberated from the polyp. Probably, therefore, 

 budding is an expression of healthy activity, vigor, and plentiful 

 food much as it is in hydra, and it doubtless occurs during the 

 entire life of the medusa. The sexual organs develop at rather 

 definite seasons, March to May being the season recorded by 

 C. W. Hargitt ('04); but this season is not sharply limited, for 

 I have found specimens later in the summer which possessed 

 gonads. 



From the description of the structure and reproductive habits 

 of these medusae it is evident that the material is almost ideal 

 for an investigation of the formation of the germ cells and their 

 possible migration from the older medusae to the budding sec- 

 ondary and tertiary ones. In other words, if there is a con- 

 tinuity of the germ plasm it should be possible to demonstrate 

 it in this form by finding germ cells migrating into the young 

 medusae which are developing asexually. The cells and tissues 

 of the medusae are greatly specialized and differentiated, far 

 beyond the amount of specialization in polyps. The cells of 

 the bell, canals and tentacle bulbs are entirely unlike any germ 

 cells in appearance; any of the latter cells should easily be 

 recognized if present. The ectoderm cells of the stomach of 

 the medusa are more like germ cells in appearance than, any of 

 the other tissues, but even if germ cells could- not be distin- 



