No. 2.] ANURIDA MARITIMA. 243 
cavity. Here they are pushed forward by those developing 
behind, and are later inclosed in follicles made from the wall 
of the ovary. The difference between this follicle and that 
usually found in the hexapod ovary is in its direct origin from 
the ovarian wall, not from certain special cells in the germinal 
epithelium. 
No further light is thrown by Anurida on the exact part 
taken by these accessory cells in the development of the ovum. 
No support is given, however, to Will’s idea of the direct 
transformation of follicle cells into the yolk (Will, 84). Cer- 
tain changes occurring in the nutritive cells previous to yolk 
formation and the disappearance of the material shown just 
preceding and during the early stages of the growth of yolk 
supports the view held by Blochmann ('84), Schiitz ('82), and 
others that the nutritive cells secrete a ferment, the precursor 
of the yolk; this passes from the cells into the ovum and then 
the yolk appears. This material is probably formed also in the 
ovum itself. The persistence of these cells up to the time of 
maturity of the ovum till all the yolk is formed, their undi- 
minished size up to this point, and their rapid degeneration 
afterwards, indicate an active relation between them and the egg. 
The existence of lines of communication between the acces- 
sory cells and the ovum, such as was seen by Claus ('64) and 
Wielowiyski (’85), is evidence of a higher degree of differentia- 
tion; probably the material passed into the ovum in cases 
where there is a visible connection is more highly elaborated 
by the nutritive cells and requires less adaptation by the egg. 
As far as the origin of these cells is concerned, it is generally 
agreed that they arise from undifferentiated germ cells; it may 
be, perhaps, owing to a peripheral position on the germinal 
epithelium that more nutrition reaches them, or some other 
less evident cause may prevail. One thing is clear, that an 
added supply of chromatin is one of the first changes; from 
an originally small chromosome the mass increases by branch- 
ing and spreading. Fine threads reach out in every direction 
as if to offer a larger area for contact with the nuclear plasma. 
It finally assumes in Anurida a strikingly stellate structure 
(Rigso10; '11;) 13); 
