ON DEVELOPMENT OP ATYEPHIKA COMPRESSA. 
407 
on this point except that I have not seen any gland other than 
those found in the oviducts. 
At an early period of development, the inner and the outer 
egg- membranes lie so closely together that it is a matter of 
great difficulty to separate them. They are both very elastic 
and are quite structureless, except that the inner egg-membrane 
is marked with the polygonal areas already spoken of. The 
newly-laid eggs show no structure like a nucleus in them. I 
have often tried by means of sections and otherwise to find out 
how the nuclei of the post-ovarian eggs arise, and how the 
spermatic elements act upon them, but I have entirely failed, as 
I did in the case of the disappearance of the nuclei. All that 
I am certain of is that the original nuclei disappear before the 
formation of fresh ones capable of segmentation, and that the 
egg probably receives the male elements as soon as they come 
out of the oviducts, for the reason that I have often observed 
a spermatophore attached on the sterna of the female during 
the breeding season. 
Judging from figs. 14 and 15 represented in Faxon’s 
“ Embryological Monographs,” pi. iv, I see that the male 
and the female pronuclei were found in the eggs of a Copepod 
(Cetochilus septentrionalis) by Grobben. In sections 
of freshly-laid eggs I have twice observed an appearance that 
may be interpreted as the process of the fusion of these two 
elements ; but this I can say only with much caution, for I 
have never seen the stages before or after it. 
The form of the egg is in general ellipsoidal, measuring 
about 0 75 — 0 85 mm. in long axis and 0*45 — 055 mm. in 
short axis. Its colour varies much according to the colour 
of the mother prawn, but is usually of a yellowish green. The 
colour of the animal varies again with the surrounding objects ; 
thus when the prawn is caught among the green grass it is 
more or less greenish, but when it is caught among the dead 
grass, which is usually the case in the late autumn and in 
winter, it partakes somewhat of the colour of hay. When, 
again, the animal is transferred from its natural habitat to a 
white dish, it gradually loses its colour in the course of a few 
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