POLYZOA OF WATBRAVOKKS. 449 



to germinate. It is well known that the statoblasts in this species 

 ordinaiily germinate without leaving the tubes in which they 

 have been produced. It need hardly be pointed out that the 

 state of the winter-buds, here as iii the Paludicella described 

 above, is such as to give every opportunity for the dispersal of 

 the species throughout the system into which it has effected an 

 entrance. In the Batley case at least (and probably in the other) 

 the branches examined were not taken from the places where 

 they had been growing in the pipes, but had become free by the 

 disintegration of the colonies at the approach of winter, and had 

 accumulated in the meters and taps to such an extent as to 

 block them. 



(3) Plumatella fungosa Pallas, var. coralloides Allman. 

 (PI. LXIII. figs. 22-25.) 



I follow Braeni (90, p. 3) in regarding Plumatella coralloides of 

 Allman as a form of F. fungosa. This seems to be indicated by 

 Allman's fig. 4 (pi. vii.) of the floating statoblasts. It should, 

 however, be noted that Annandale, in his recent account of the 

 Indian species (11, pp. 217, 218), gives P. coralloides asasvnonym 

 of P.fruticosa. 



In dealing Avith representatives of the genus Plumatella one 

 is confionted with numerous difficulties ; since there is no 

 general agreement with regard to the species which ought to be 

 recognised. It is worth remembering that Plumatella has three 

 different kinds of reproductive bodies, namely, the embryos 

 produced by the development of the eggs, the floating statoblasts, 

 provided with an " annulus " of gas-containing cavities, and the 

 sessile statoblasts. We are in almost complete ignorance with 

 regard to the question whether the form of the colony depends 

 to any extent on the particular kind of reproductive body from 

 which it has been developed. As Braem has pointed out (90, 

 p. 8; 11, p. 9), experimental evidence on this subject is urgently 

 needed ; and it is probable that a well-conceived series of bi-eeding 

 experiments carried out with statoblasts and embryos of Plumatella 

 might resolve some of the difficulties which at present exist. 

 Braem (90, p. 6) has recorded the important observation that in 

 cases where the remains of the statoblast from which a colony 

 has germinated can be detected at the pi-oximal end of the 

 colony, the form of that statoblast can sometimes be proved to 

 be identical with those which are being produced in the tubes of 

 the same colony. There are reasons for believing, as has been 

 remarked above, in dealing with Paludicella, that ovaries and 

 testes are usually produced early in the summer from colonies 

 which have resulted from the germination of statoblasts or 

 hibernacula (cf. Ki-aepelin, 87, p. 85). But it has not been 

 sufficiently ascertained how far, if at all, these sexually mature 

 colonies differ from those produced by statoblasts ; nor is it 

 known whether there are any difierences between colonies 



