104. TRANSACTIONS OF THE ROYAL CANADIAN INSTITUTE  [VOL. XI 
not have as large gonads as the older and larger, the proportion to 
the whole weight seems to vary within a comparatively narrow range. 
The eggs when ripe are 1.4 to 1.6 mm. in diameter and in weight run 
from 900 to 1000 to the gram weight of the ovary. In the female in 
which the single ovary weighed 18.6 grams there were approximately 
35,000 eggs, but this size is exceptional, and in all probability there are 
few cases in which there are more than 30,000 even in the older fish, 
while in the younger a very much smaller number is found. Ina single 
ovary there were 14,165 eggs—making 28,330 to the fish—by actual 
count, while in a smaller fish there were 9,489 eggs in one ovary or 
18,978 eggs to the fish. The yolk fills a large portion of the egg mem- 
brane, and there are no oil globules present. 
The development of the embryo in the egg is easily studied, as, not 
only is the membrane transparent so that the embryo and the yolk 
may be seen without difficulty, but it is also very tough so that the eggs 
will stand handling without causing harm to the embryo. The spawn 
from a ripe female may be squeezed out into a dish containing fresh 
sea water into which sufficient milt is put at the same time. The eggs 
adhere to the bottom of the dish, hence the water can be changed on 
them readily—twice a day being sufficient—so that little care is re- 
quired to get the development to take place as successfully as if it were 
in the sea itself and therefore as satisfactorily as could be desired. It 
is possible to get all but the earliest stages readily by getting the sea- 
weed at the spawning ground from time to time and keeping it fresh 
until the next lot is obtained. Unless new material is obtained often, 
this does not prove so satisfactory as hatching the eggs out in a dish 
with no seaweed in it, as when the seaweed is torn from the rocks it 
decays quickly and apparently poisons the water as the embryos, 
particularly if they are nearly hatched out, die off rapidly. As the spawn 
in the natural condition is subject to a variety of temperatures on 
account of being exposed directly to the sun while the tide is out, a 
constant temperature is not necessary when hatching eggs under obser- 
vation. If the temperature is kept high, development takes place more 
rapidly within comparatively narrow limits, but there is a higher mor- 
tality. The best results are obtained when the temperature is kept 
much the same as the temperature of the sea water, which at that time 
is between 45° and 50° F., at which temperature, with other conditions 
satisfactory, there should be almost no loss. The rate of development 
considered in the following account corresponds to that which takes 
place at such a temperature. 
Very soon after the ovum is shed the eelmarneaee enters and 
fertilisation takes place. In less than two hours the first furrow in the 
