28 THE EGG HARVEST. 



that thirty minutes is long enough to leave them, some say twenty 

 minutes, and one late authority says one minute. I should rather 

 leave them together forty-five minutes than less. It depends, 

 however, very much on the temperature of the water, the adhesive 

 period lengthening as the temperature decreases. You are more 

 likely to err on the safe side by keeping them too long together 

 than by not keeping them long enough." (Domesticated Trout, 

 p. 103.) And under the caution that it is quite possible to 

 suffocate eggs by over-milting, I cordially indorse the above. 

 The cause of the adhesion of the ovum is not clearly understood, 

 but I incline to attribute it to suction. The shell of the egg is 

 marked with a large number of contiguous round spots which I 

 think are pores. The egg when first milted feels very soft to 

 the touch, and assumes a remarkable bloom, which I am inclined 

 to attribute to the action of the water. After the eggs have 

 separated they feel firm and hard, and produce a sensation to 

 the hands, when passed through them, similar to the feeling of 

 stirring dried peas in a bowl. This must be due to increased 

 tension of the shell, produced by water being absorbed by the 

 contents of the egg ; the micropyle is probably closed subsequent 

 to the entrance of the spermatozoon, and the water absorbed 

 through the pores of the shell. The adhesion is easily explained 

 on the principle of a boy's leather sucker. 



The bloom visible on the ovum is perhaps produced in the 

 same manner. When ova are left for some time with undiluted 

 milt, washed, and at once placed in the collecting-pails, without 

 regard to the time of adhesion, white eggs picked out from the 

 trays next morning frequently exceed 10 per cent, of the whole 

 ova, while 1 per cent, would be considered an extraordinary loss 

 at Howietoun. When the milk-plates are ready to pour, a collect- 

 ing-pitcher one which will hold three gallons of water is the most 

 convenient size is filled with water, and the ova poured over the 

 spout of the milk-dish into the centre. The ova, being heavy, fall 

 slowly to the bottom, while any empty shells are carried away by 

 the overflow. When the pail is a little more than half full of ova 

 it is immersed in one of the built inlets to the ponds, where the 



