578 EEPORT 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 iish in a definite proportion; the unit is technically called 

 a "spawning part3\" 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 Cyprinidge and some of the 

 Catostomidffi, 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 [CatostoTnus com/mersonii)^ 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 the}^ 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 directl}' upon the temperature 

 of the water. In temperate regions, under favorable conditions, they are 

 said to hat(;h 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 



