580 
BULLETIN OP THE BUREAU OF FISHERIES 
eggs apparently ranges from about 12 to 24. During development these colored 
bodies become less and less definite in outline, and in advanced embryonic stages the 
color becomes paler and diffuse, often disappearing entirely several days before the 
egg hatches. 
Golden yellow oil globules are also present. These spheres are equally as variable 
in size within an egg and in number in different eggs as the old- rose colored bodies. In 
general they are somewhat concentrated near the blastoderm. The oil globules persist 
in part at least until the egg hatches or even in the small yolksac attached to the newly 
hatched fish. In the accompanying drawings the old rose colored bodies are shaded, 
while the oil globules are unshaded. Some of the variations in the shape of the colored 
bodies are shown in the illustrations. The total number of colored bodies and oil 
globules is not shown. Those indicated are the ones which came into focus under the 
microscope at one level. 
The egg, furthermore, has a large central body, apparently denser in texture than 
the rest of the egg, grayish in color like the adhesive disk, and quite opaque. This 
body disappears in the advanced embryonic stage. A similar central opaque body 
is present also in the eggs of the other two species of blenny discussed elsewhere in 
this paper. 
The entire egg is moderately opaque, becoming more so as development proceeds. 
Fair perception is obtainable, however, in recently spawned eggs if viewed in a plane 
parallel with the surface to which they are attached. In the opposite direction the 
dirty -gray opaque adhesive foot, which cannot be detached without injury to the egg, 
and the opaque central body obscure vision. The yolk is granular in appearance. 
The egg membrane has deep lines and elevations, suggesting rugged eroded land. 
This sculpture on the egg case is not shown in the accompanying illustrations. 
Segmentation and the development oj the embryo— The eggs forming the bases for 
the present account were taken in nature. The exact time of fertilization is not known. 
Therefore, the length of the period intervening between fertilization and the beginning 
of cell cleavage cannot be stated definitely. The earliest cell division stage found, 
namely four cells, occurred in two nests taken at 8:30 o’clock in the morning. These 
eggs probably had been laid 2 hours or so before the nests were found. This tentative 
conclusion is based on the results obtained with Hypleurochilus geminatus (p. 593). 
In that species segmentation started about 2 hours after fertilization. It seems reason- 
able to expect that the intervening time in these related species would be about equal 
at the nearly identical temperatures which prevailed (28° to 28° C.). 
The blastodisc is apparently always situated next to the adhesive disk. This 
position of the blastodisc makes it difficult to observe cell division, as the opaque 
adhesive disk below and the opaque central body above it obscure vision. Fortunately, 
eggs in the early stages are more transparent than those in the more advanced stages. 
Consequently, it was possible to see the cells, even though dimly, through the mass of 
the egg (fig. 75). In a lateral view the cells could be seen more definitely. The first 
blastomeres apparently are about equal in size and the second cleavage cuts the blas- 
todisc at right angles to the first. The perivitelline space is comparatively large at 
the positive pole and very small or wanting at the negative one (fig. 76). 
Segmentation proceeds rapidly, the 8- and the 16-cell stages (figs. 76 and 77) fol- 
lowing the 4-cell one at intervals of about 30 minutes each at a water temperature of 
about 26° C. As development proceeds the egg becomes more granular, and it 
becomes more and more difficult to see exactly what is taking place. While the 
blastoderm no doubt is dome-shaped, as usual in teleosts, it cannot be seen because of 
the opaqueness of the yolk (fig. 78). An advanced cleavage stage is reached in about 
