FEETILISING TROUT EGGS 131 



stripped into a dry pan many of them would 

 stick to the sides and bottom, and most of those 

 which so adhered would in a little while become 

 affected by fungus and die. The remainder 

 would not become fertilised and consequently 

 would not hatch. The moist pan prevents ad- 

 hesion. 



Artificial Fertilisation. — All the preliminaries 

 having been completed the men are now ready 

 to "take" and impregnate eggs. The ovaries 

 of the brook-trout are two membranous sacs 

 lying along each side of the backbone of the fe- 

 male, in which the eggs are developed, growing 

 larger until early in the fall, when, shortly be- 

 fore being voided, they attain their full size 

 previous to being fertilised, and can be ex- 

 pressed easily from the fish by a slight pressure 

 of the fingers on its belly. On both sides of the 

 backbone of the males are the testes, in which 

 are formed spermatozoa, or fertilising ele- 

 ments. They are pendant-shaped, with the 

 points towards the vent. As the spawning time 

 grows near, the pointed ends become soft, and 

 there exudes a milky liquid called "milt," bear- 

 ing thousands of spermatozoa. This milt may 



