606 
BULLETIN OF THE BUREAU OF FISHERIES 
The eggs as seen on an oyster shell with the unaided eye are very pale yellow. 
Under magnification just a tinge of yellow is evident. Numerous yellowish oil 
globules, mostly in that half of the yolk nearest the adhesive disc, are present. The 
eggs have a dense opaque central body, as in the other blennies studied. No bluish 
or reddish spots are present in the yolk and therein the eggs of this species differ 
conspicuously from those of the other local forms. 
The eggs of this species apparently are even more opaque than those of the 
other blennies studied. The yolk is quite granular, becoming more so as develop- 
ment progresses. The egg membrane is cellular in appearance. When the microscope 
is refocused the lines have the appearance of deep ravines with elevations between 
them. This sculpture of the egg membrane is not shown in the accompanying 
illustrations. The adhesive disk described above, is shown in only one drawing 
(fig. 118), although of course it is always present. 
Figure 112 . — Chasmodes bosquianus. From egg in 2-cell stage; 
about 2 hours after fertilization. (Drawn by Nell Henry.) 
Figure 111. — Chasmodes bosquianus. From egg with blast- 
odisc; shortly before the first cleavage; probably about an 
hour after fertilization. (Drawn by Nell Henry.) 
Segmentation and the development of the embryo . — The following account is based 
entirely upon eggs collected in nature. The exact time of spawning and fertilization 
is not known. Therefore, the time intervening between fertilization and the begin- 
ning of cleavage cannot be stated definitely. In a nest taken at 9:30 o’clock in the 
morning eggs were present in which the first cleavage took place about an hour after 
collection. It seems probable that these eggs were laid early on the morning the 
nest was brought to the laboratory, as already explained (p. 605). In Hypleurochilus 
geminatus about 2 hours intervened between fertilization and cleavage at a temperature 
of 26° to 28° C. It probably may be assumed that in Chasmodes about an equal 
length of time elapses between fertilization and segmentation, at nearly identical 
temperatures. 
The blastodisc in all the eggs examined lay next to the adhesive foot by which it 
was largely obscured when viewed in the normal position. However, when the egg 
was turned so that the adhesive surface of the disk was at right angles to the side upon 
which it rested, a fair lateral view of the blastodisc and segmentation was obtainable. 
Accordingly, the illustrations showing different stages of cleavage are all lateral views. 
In general, only that part of the disc extending beyond the yolk is shown, as the 
opaqueness of the egg obscured the rest. 
