DEVELOPMENT AND LIFE HISTORY OF SOME TELEOSTS 
583 
and these together with the large vein in the embryo all pour their contents into the 
heart which has somewhat the appearance of a pit. Corpuscles are plainly evident, 
and from their rapid progress it is obvious that circulation is brisk. The old-rose 
colored bodies previously present have disappeared. However, some eggs retain a 
diffuse pinkish cast in the yolk near the heart of the embryo. The embryo is capable 
of much movement. The tail is free and is switched frequently. The embryo is 
able to turn within the egg membrane, carrying the yolk with it in its movements, 
(fig. 83). 
Progress in the development after about the sixth day of incubation seems particu- 
larly slow. The embryo increases little in length and the yolk is absorbed very slowly. 
Dark markings on the yolk, which tend to decrease in size after about the fourth or 
fifth day of incubation, generally disappear entirely a day or two before hatching. 
In the meantime black markings become evident on the embryo. A rather large 
branching blotch is present on the head between the eyes, numerous black chroma- 
tophores also appear on the comparatively large pectorals, and short branching cross 
lines mark the myomeres along the ventral 
surface of the caudal region of the embryo. 
Just before hatching the egg becomes some- 
what distorted, the egg membrane being 
pushed out somewhat at the head of the 
embryo. 
Eggs taken on May 31, 1932, which 
were in several different stages of develop- 
ment, ranging at the time of collection from 
a rather advanced cleavage stage to a stage 
in winch the embryo already was well differ- 
entiated, hatched from June 8 to 12. The 
temperature of the water during this tune 
varied from about 25° to 27° C. The 
eggs in a nest taken June 16, 1932, which 
ranged in development about equally as 
much as those taken on May 31, hatched 
from June 24 to 26. The temperature of 
the w r ater during this period varied from 
about 24.5° to 27° C. Assuming that the 
last eggs hatched in each nest were those which were in an advanced cleavage stage 
when taken, and that these eggs were laid on the day of collection (concerning which 
there can be little or no doubt), the incubation period has a duration, at the tempera- 
tures stated, of about 10 to 12 days. The incubation period in this species, therefore, 
is longer than in Hypleurochilus geminatus (see pp. 596 and 610), and about the same 
as in Chasmodes bosquianus. 
Hatching, like spawning, apparently takes place early in the morning. At the 
time of hatching, the yolk was almost wholly absorbed and the young fish generally 
died by the evening of the day on which they were hatched. However, for 4 days in 
succession a new lot was present each morning. Several efforts were made to keep the 
fish alive and to induce them to feed and to grow. Some were kept in a tank with 
ru nn ing water, others were transferred to shallow glass bowls with standing sea water. 
The lots in running water were not fed, those in standing water in part were offered 
towings and in part very finely minced oyster. However, none lived more than 2 
154970— 3S 6 
Figure 83 .—I-Iypsoblennius hentz. From egg with large 
embryo: about 6 days after fertilization. H, heart. Arrows 
show direction of blood flow in the larger vessels. (Drawn 
by Nell Henry.) 
