ARTIFICIAL IMPREGNATION. 79 



greatly the handling of the fishes. The operator 

 loses no time (which, with the thermometer at 

 zero, is doubly precious) in selecting his subjects 

 for operation. The form of the pan in which the 

 impregnation is to be accomplished is a matter of 

 little moment. It has been done in the top of a tin 

 wash boiler; yet some suggestions on this point 

 may be important. Whatever is used it must be 

 thoroughly clean ; a drop of grease will prevent 

 the fertilization of thousands of spawn ; it must be 

 smooth, as the freshly-taken spawn may be killed 

 by coming in contact with any rough surface. 

 Perhaps the best articles for the purpose are china 

 soup-plates of the largest obtainable size. These 

 will hold about one thousand eggs each. The only 

 objection to their use is the ease with which they 

 are broken ; and a good, new, well-polished tin 

 basin ten inches in diameter and three deep will, if 

 kept clean, answer the same purpose, with less 

 danger of breakage. If it is desired to know at 

 once the number of spawn taken, it is readily 

 ascertained by having a depression sunk in the 

 bottom of the pan eight inches long, five wide, and 

 one-sixth of an inch in diameter; this will hold 

 one thousand average spawn. All things being 

 ready, the pan is filled to about one-third of its 

 capacity with pure water, and a female is taken 

 and held in the position represented in Fig. 16, the 



