GERM CELLS IN PEDICELLINA AMERICANA 5 



Others, who have urged the probabihty that sex is not directly 

 subject to the action of external stimuli, but is rather inherent 

 in the germ-cells. 



The relations described in Pcdicellina may best be interpreted 

 in the light of the facts observed in other colonial forms. 

 Throughout the Coelenterata, with the exception of such hema- 

 phrodites as Chrysaora and Hydra and such colonies as Coral- 

 Hum rubritni and some of the Sertidaria (cf. Cuenot), the 

 individuals of a colony are all of the same sex. In the Ecto- 

 proctous Bryozoa and the Tunicates, on the other hand, the 

 conditions are still simpler, for among these the individuals are 

 all hermaphroditic. In the Endoprocta all possible conditions 

 as to sex exist, as the following rcsinne will show. 



In Loxosoma annelidicola, the individuals, according to Prouho, 

 'oi, are all of one and the same sex. No permanent colony is 

 formed. Loxosoma davenporti, as described by Nickerson, 'oi, 

 is hermaphrodite throughout, but there is distinct proterogyny. 

 In Hke manner, Harmer, '85, found in L. pes and in other 

 species of this same genus, hermaphroditism, with a decided 

 proterandry. Finally, in L. raja, as early described by Schmidt, 

 '^6, simple hermaphroditism prevails. In the genus Fedicellina 

 proper, like variations occur. According to both Nitsche, '69, 

 and Hatschek, ''jj, the individuals of P. echinata are herma- 

 phrodite, while according to the late investigation of Harmer 

 '85, and Fcettinger, "^j , they are of one sex. The weighty 

 opinion of Ehlers, '90, however, who himself investigated the 

 problem, is on the side of the former. A like difference of 

 opinion is found in connection with P. bencdeiti v^hich, according 

 to Fcettinger, is dioecious, but by Ehlers is as positively regarded 

 as mtonoecious. P. belgica, on the former authority, is also 

 dioecious, while on that of the latter, P. glabra, is monoecious. 

 Finally, in P. americana, and in the nearly allied Ascopodaria 

 macropus, the individuals are always either male or female, but 

 both may occur in the same colony. 



The disagreement that exists among the different authorities 

 mentioned, concerning the sex of a considerable number of 

 forms, is a striking fact. It is difficult to suppose that good 



