610 GEORGE T. HARGITT 



made from preserved individuals, both figures show the general 

 character of the medusae, and its habit of budding other medusae. 



The medusae produced by budding from the base of the single 

 tentacle are liberated to become free swimming and independent 

 individuals. A good many of these secondary individuals may 

 be formed from the primary medusa and as they in turn produce 

 new medusae by budding there is a great lengthening of the life 

 cycle of the animal and a tremendous extension of its range. 

 While there are commonly a good many buds present in various 

 stages of development on any one individual, it may be that 

 others will show only a single bud or be without buds. The 

 developing medusae may begin to produce small buds even 

 before they are themselves liberated, and it is possible to find 

 several generations present at the same time. On the other 

 hand the budding process may begin only after liberation. The 

 budding continues for a long season since medusae captured at 

 almost any time in spring, summer, or autumn possess the buds. 



In addition to this asexual method of reproduction in the 

 medusae there is the usual sexual method. Each medusa is a 

 sexual individual and produces either eggs or sperms on the 

 sides of the manubrium (figs. 38, 39). The eggs are not dis- 

 charged from the gonad but are fertilized in place, and develop- 

 ment of the eggs proceeds till a young polyp or actinula is 

 formed. The actinula is freed from the parent medusa and 

 starts the new hydroid or polyp generation. Figure 39 shows 

 a section of such an actinula on one side of the stomach wall of 

 the medusa and a part of the ovary on the other side. This 

 fact of sexual and asexual reproduction occurring in the medusa 

 has been known for a long time; the same condition exists in a 

 few other medusae also, though asexual reproduction is not 

 common in medusae. Furthermore it has been shown that both 

 methods of reproduction may take place at the same time. C. 

 W. Hargitt ('02, '04) and Perkins ('04) have both noted the 

 occurrence of these two methods at the same time and Mayer 

 ('07) calls attention to it. A large number of specimens exam- 

 ined by the author showed no correlation between the time 

 of formation of the medusa buds and the formation of the germ 



