LACINULAKIA SOCIALIS 135 



This, however, stops short a Httle distance from the extremity, and 

 forms a transverse diaphragm, from the centre of which a bunch of 

 long and excessively delicate seta; proceeds (fig 29). I could observe 

 no trace of any aperture with a power of 600 diam., though, of course, 

 this is merely negative evidence. 



Is it not possible that, as the " ciliated sac " of the Ascidians 

 has its analogue in the " fossa " of the Rotifera, so the calcar may 

 answer to the " languet," which has a similar relation to both sac and 

 ganglion ? 



In Notominata there is no calcar, but nervous cords proceed from 

 the ganglion to the ciliated spots about the middle of the dorsal 

 surface (Dalrymple). 



Reproductive Organs. — Considering Professor Ehrenberg's deter- 

 mination of the male organs to be set aside, his description of the 

 reproductive organs extends only to the ovary, which, he says, in 

 Lacinularia " lies in the posterior cavity of the body, and has thus one 

 and the same outlet with the intestine " (p. 403). This seems to imply 

 an oviduct ; I could, however, see no such organ.i The ovary consists 

 of a pale, slightly granular mass of a transversely elongated form 

 (fig. 5 /), and somewhat bent round the intestine ; it is enclosed within a 

 delicate transparent membrane, which is hardly visible in the unaltered 

 state, but becomes very obvious by the action of acetic acid, which 

 contracts the substance of the ovary, and throws the membrane into 

 sharp folds. 



Pale clear spaces, which sometimes seem to be limited by a dis- 

 tinct membrane, are scattered through the substance of the ovary and 

 in each of these a pale, circular nucleus is contained. The nucleus 

 is more or less opaque, but usually contains 1-3 clear spots (fig. 9). 



These are the germinal vesicles and spots of the future ova. 

 Acetic acid, in contracting the pale substance, groups it round these 

 vesicles, without, however, breaking it up into separate masses. It 

 renders the nuclei more evident. 



The ova are developed thus : — One of the vesicles increases in 

 size, and reddish elementary granules appear in the homogeneous 

 substance round it (fig. 10). This accumulation increases until the 

 ovum stands out from the surface of the ovary, but invested by its 

 membrane, which, as the ovum becomes pinched off as it were, takes 

 the place of a vitellary membrane. 



In the meanwhile the germinal vesicle has increased in size 

 and its nucleus is no longer visible. In the ovum it appears as a 



1 Leydig [loc. cit. p. 469) says that there is a wide oviduct which becomes folded when 

 .empty. I must leave the discrepancy until a further examination decides which is right. 



