492 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [2] 
forated box), placed in the water, or it a large cage furnished with floats* 
(Fig. 2), which is so placed as to insure all the conditions necessary for 
the health of the fish. One may also use the box depicted in Figure 
17 after having taken 
out the hatching frames, 
“which are no longer 
needed. 
In case it should be 
impossible to procure 
live fish for the purposes 
of propagation, it will be 
necessary to operate 
with fish which have 
Fic. 2. been dead for two or 
three hours or more. It is well known that the milt contained in the 
genital organs retains its fecundating property for a long time, and 
does not even lose it through frost; but we still lack positive and exact 
data as to the length of time in which eggs will retain the faculty of 
being impregnated by spermatozoa with regard to changes of temper- 
ature and to the different kinds of fish. Nothing but continued obser- 
vations will lead to the solution of this problem.t 
Towards the time when it may be assumed that the fish which are to 
be propagated are ready to lay their eggs, they must be watched so as 
to take them in the exact moment when the eggs are about to be laid. 
The following external signs indicate the near approach of this moment: 
The belly of the female is slightly distended, the anal opening is very 
moist and swollen and protrudes like a hemorrhoidal tubercle; the eggs, 
surrounded by an abundant ovarian secretion, are free from all connec- 
tion and may by the slightest pressure be moved about in the cavity in 
which they have fallen. These eggs do not change color until they have 
come in contact with the water. 
These symptoms are less pronounced in the male, but the slightest 
pressure on the abdominal walls provokes the emission of the milt and 
leaves no doubt as to the approach of the spawning period. One can 
now proceed with the fecundating process, which may take place in 
two different ways, according to the distinction made between fish lay- 
ing free eggs, such as the trout, salmon, &c¢., and those whose eggs adhere 
to other bodies, such as the tench, carp, gudgeon, &e.t 
*J. Lamy: Eléments de pisciculture, Paris, 1855. 
tIt has been stated that eggs extracted from dead female trout and salmon, although 
beginning to show a change, were still endowed with the faculty of being fecundated 
by the milt from a male fish in the same condition; and the Munich piscicultural es- 
tablishment frequently works with eggs bought in hotels or from fishermen. The re- 
sult, however, is never as complete as with eggs from live fish. 
fCosTE: Comptes-Rendus, 1852, i, 985, 
