ARTIFICIAL PROPAGATION 



191 



conceal them from view. In a few minutes, three or four, another 

 quarter of an inch of water may be added. The eggs meantime have 

 coagulated in mass. Then the basin must be left perfectly still for a 

 time, which may be anything from twenty minutes to two hours, 

 according to the temperature, the longer time being required in colder 

 weather. With sea-trout, which spawn earlier than salmon, one seldom 

 has to wait longer than half an hour, and the period may be employed 

 carrying out a second " drive " and spawning a second batch of fish. 



During the period of quiescence the mass of eggs is disintegrating 

 and any disturbance during this process must be avoided. But now 

 and then, when he thinks " time is up," the operator may gently tilt the 

 basin to one side to see if the eggs are now separated, when, if they are, 

 the process of fertilisation is over. He now washes the eggs clear of 

 all the milky fluid by pouring fresh water into the basin till all is pure 

 and the eggs lie, a beautifully tinted mass (yet all separate), in the 

 bottom of the basin. Each lot of eggs is in turn poured gently 

 into the tin pails for the homeward journey, and no more than an inch 

 or two of water need cover them during transport. Once fertilisation 

 has taken place a reasonable amount of unavoidable disturbance does 

 not seem to be harmful to the eggs, so they are placed beside us on 

 the car when we have got all our traps put together. 



Arrived safely at the hatchery the ova has now to be deposited on 

 the grilles or in the zinc baskets. This requires no more than neatness 

 and care, an enamelled cup being used to ladle out the eggs from the 

 pails. If we are working with glass grilles, no more ova must be placed 

 on each frame than will occupy exactly the available space. Each 

 little rack must contain its exact quota of eggs, so that when the frames 

 are filled all the eggs will be uniform in rows, and all the rows uniform 

 in the box, with half an inch of water passing gently over them. Tf we 

 are using the perforated zinc baskets, each may safely be filled with two 

 or three layers deep of ova in mass, but at least three-quarters of an 



