262 TEE AMERICAN NATURALIST [Vol. LVI 



Name's contention that this function can not be acquired 

 when once lost. 



The fact that the sessile forms contain more persistent 

 types (corals have 15 per cent., bryozoans 22 per cent.) 

 than the vagile benthos would suggest that budding may 

 be a mode of asexual reproduction favorable to the per- 

 sistence of types; and that it may be the cause of the 

 large percentage of persistent types among the sessile 

 forms. It must here, however, be considered that also 

 the sessile Cirripedia which lack the function of bud- 

 ding, have furnished 20 per cent, of persistent types; 

 and further that in all the classes here considered bud- 

 ding is associated with sexual reproduction, often, as in 

 many ca?lenterates, in a regular alternation of genera- 

 tions. Moreover, the sexually reproducing brachiopods, 

 gastropods and pelecypods have furnished large percen- 

 tages of persistent types, a large number of which are 

 sessile forms. 



While thus budding would not seem to be the control- 

 ling factor in the persistence of the sessile forms, it is, 

 nevertheless, true that budding may have a distinctly 

 retarding effect upon the evolution of such forms, prin- 

 cii)ally by the material decrease of the cases of sexual 

 rei^roduction. As in the case of the corals, the number of 

 new stocks that originate from sexual reproduction and 

 finding a new lodging place, start new colonies, is very 

 small when compared with the number of asexually pro- 

 duced individuals on the stocks. There are therefore 

 many more generations of asexually than sexually pro- 

 duced individuals. 



(c) Reproduction by Hermaphrodites.— Another factor 

 that possibly may have contributed to the persistence of 

 forms is hermaphroditism. Claus has pointed out that 

 hermaphroditism finds most abundant expression in slug- 

 gish and fixed animals. " Among sponges, sea-anemones, 

 corals, Polyzoa, bivalves, etc., we find frequent illustra- 

 tion of the association of fixedness and hermaphroditism " 

 (Geddes and Thompson, op. cit., p. 83). The origin of 



