VIVIPAROUS FISHES OF THE PACIFIC COAST. 
415 
As I have stated before, food absorption is probably continued by parts of the 
general surface throughout intraovarian existence, and is greatly facilitated in later 
stages by the highly vascular fins. 
The food absorbed and digested is furnished by the ovarian lamellae themselves. 
These structures are much greater than is necessary to bear the few eggs, and they 
are so constructed that they offer the greatest uninterrupted surface possible. 
The intraovarian food entering the intestines consists in great part of solid cell- 
like particles. These are found both in the gravid ovary and in the intestine of the 
embryo. They, together with the ovarian fluid, are the product of the lining epi- 
thelium. The individual cells of this structure become distended with an unstainable 
fluid. At the outer margin of these distended cells are seen nucleated bodies in all 
stages of separation from the epithelium. At first I supposed them to be the product 
of the epithelial cells, but am more inclined now to consider them the cells themselves 
deprived of their fluid contents. These cells are found in the intestine of the larvae, 
in early stages, few in number, in later stages forming a solid mass. 
The amount of fluid in the ovary at any time is very small in C. aggregatus , but 
is very much greater in some other species. Till the young has attained a length of 
several millimeters there is no more of it than there is serum in the body cavity. In 
the later stages, when the lamellae are stretched to their utmost and the highly 
vascular surface of the fins is brought in contact with them, direct dialysis, primarily 
for oxygenation, probably takes place between the cells of the ovarian lamellae and 
those of the young. 
Intraovarian respiration . — That there is the closest intimacy between the respira- 
tion of the mother and young has been proved by the fact that the latter shows signs 
of asphyxiation before the former shows exhaustion, i. e., if the mother is kept in stale 
water; if she is taken from the water she will die before the young. The embryo and 
larvae are at all times in contact with the structures of the ovary which derive their 
blood directly from the gills. During the early stages the highly active spermatozoa 
keep the ovarian fluid in circulation and thus help the ciliated lining of the intestine of 
the larva to bring oxygenated albumen from distant parts of the ovary; while later the 
highly vascular fins and general surface of the body are in direct contact with the 
ovarian sheets. As the body becomes covered with scales the surface of the fins 
increases. It has already been stated that partly asphyxiated young can readily be 
revived by exposing them to the air in some of the ovarian fluid, a fact which seems to 
demonstrate the affinity of this fluid for oxygen. Respiration is probably also carried 
on through the stream of ovarian fluid flowing through the intestine, as Stuhlmann 
has suggested for Zoarces. The young, unless they have nearly reached maturity, 
invariably die if they are placed in either fresh or salt water. 
Duration of gestation and adolescence, and number of young. — The exact date at 
which the young are set free I am not able to tell. Some are freed as early as April, 
while others are not freed till June. The probable duration of gestation, counting 
from December 1 to May 1, is five months. The following February the smallest 
individuals are sexually mature. The time from the birth of one generation to the 
beginning of the next is therefore about ten months. Usually all the eggs in an ovary 
are equally developed ; only rarely was any marked difference observed. In one case 
one young was apparently four weeks older than the others. 
