96 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



and the operation repeated till all the eggs are extruded. The eggs 

 are immediately impregnated with milt, which is obtained from the male 

 in similar manner, except that more force is necessary and the pressure 

 is made at a point about midway between the ventral and anal fins. 



The contents of the pan are next lightly stirred with a feather to 

 insure impregnation of all the eggs possible. They now present a 

 milky appearance and are washed in as many changes of water as is 

 necessary to thoroughly cleanse them from the milt and other refuse, 

 when the pan, left half filled with fresh water, is placed in running 

 water to keep the eggs at a low temperature. After from 30 to GO min- 

 utes, according to the temperature of the water, the separation of the 

 eggs ensues. 



In the work on the Au Sable Elver, the eggs, after separating, are 

 laid on gravel placed i inch deep in the boxes of the troughs. Here they 

 remain till tbe eye-spots begin to appear, when they are prepared for 

 shipment. During this interval of about thirty days the principal care 

 consists in sorting out bad eggs, and, with a feather, gently changing 

 the position of good ones to prevent sediment from collecting on them. 



SHIPPING GREEN EGGS. 



Green eggs can be safely moved at any time up to and including the 

 eighth day. They are shipped from the field station to the hatchery in 

 cubical boxes constructed i'rom ^-incli piue lumber, just large enough 

 to admit, with a surrounding air-sj)ace of ^ inch, 19 canton-tlannel trays, 

 18 inches square on the inside, the frames of which are made from |-inch 

 square white pine. The eggs are drawn by means of a siphon from the 

 gravel boxes into a tub or bucket which has been half filled with water 

 to prevent them from injury. Using a graduated dipper for the pur- 

 pose of ascertaining approximately the number of eggs necessary to 

 make them about two deep on the tray, the packer pours them upon 

 the flannel and spreads them as evenly as possible with a feather. The 

 tray is then placed in the box and the operation repeated until eighteen 

 trays are filled with eggs. The nineteenth, or top tray, is usually left 

 empty, but if the weather is verj- warm it is filled with fine ice. The 

 cover is then fastened down, the box marked, and the eggs are ready 

 for shipment to the hatchery. 



THE HATCHING APPARATUS. 



After a period of about thirty days on the gravel, the eggs are taken 

 up and placed in the Clark hatching box, for here they may be held 

 without any appreciable loss through the escape of fish when hatching. 

 This apparatus as used at Northville is arranged as follows: A tank 15 

 feet long, with a partitioji running its entire length, is so placed that 

 its lower end rests upon the upper end of a similar one 13 feet long, 

 which differs from the upper one only in that it contains two boxes less. 

 Mne partitions, placed crosswise of the tank, form, with the lengthwise 

 partitions, a double row of eight compartments, each of which is 19J 



