578 REPORT OF THE COMMISSIONER OF FISHERIES. 
and in some places aquatic plants, because the female fish like to rub 
against stones for the purpose of ridding themselves of the roe”—a 
statement that I know of no observations to support; it seems much 
more probable that the eggs are extruded entirely by muscular action 
while the fish are swimming about. 
In pond culture the breeding ponds are usually stocked with male 
and female fish in a definite proportion; the unit is technically called 
a ‘spawning party.” Usage differs as to the relative number of each 
sex that is best for stocking a breeding pond, but it is customary to 
put in a larger number of females than males. It is usually planned 
that each ‘‘spawning party” shall consist of one ‘‘milter” and two 
‘*spawners,” or else two ‘‘milters” are provided for three ‘*‘ spawn- 
ers,” while for each three milters is added one 3-year-old male fish, 
known as a ‘‘driver” or ‘‘enticer,” which is *‘ not used for spawning, 
but simply to drive or entice the other fish to that process.” 
According to Hessel (1881, p. 872), the male carp at the breeding 
season assumes a secondary sexual character which is common to many 
members of the family at that time, namely, a various arrangement of 
‘* protuberances, like warts,” which are generally known as ‘pearl 
organs.” In the case of the carp these are said to occur on the skin 
of the head and back. I do not remember ever to have seen them on 
a carp myself, and have no mention of them in my notes. If they are 
regularly present in these positions they undoubtedly function as Pro- 
fessor Reighard has found they do in other Cyprinidz and some of the 
Catostomide, in helping to hold the female at the time of spawning— 
observations which have not as yet been published in detail (abstract 
Reighard, 1904). The method of the carp would seem to be much like 
that of the sucker (Catostomus commersonii), where the two males lie 
one on each side of the female, holding her firmly between them with 
the help of the pearl organs along the sides and tail. 
Hessel also states that sometime before the spawning season sets in 
the pharyngeal teeth fall out and are renewed each year. On this 
point I have no observations. 
The eggs are not laid in bunches or masses, but are scattered about 
in the water, and, being adhesive, they become attached to the roots 
and stems of grass and other aquatic vegetation, or to whatever objects 
chance to cover the bottom where they are deposited. The fate of 
the egg probably depends to a large extent upon where it chances to 
become attached, for should it fall into the mud there would be little 
chance for its further development. The eggs develop rapidly, but the 
time required for hatching depends very directly upon the temperature 
of the water. Intemperate regions, under favorable conditions, they are 
said to hatch in about twelve days, though if the weather be so cold 
as to lower the temperature of the water it may take them sixteen or 
twenty days to reach their full development. In the warmer waters of 
