1916 



Smith; on Salmon Development 



91 



The principal observations were made on the eggs and young of the 

 Chinook salmon (Oncorhynchus tschawytscha) , and a check experiment 

 was made on the eggs and young of the humpback salmon (Oncorhynchus 

 gorbuscha). 



The eggs of the Chinook salmon were spawned September 27, at the 

 State hatchery located at Auburn, Washington, and were brought to the 

 hatchery on the campus October 31. The eggs, over 8,000 in number, 

 were taken from one basket and were less than half of the number con- 

 tained in the basket. All the eggs were spawned the same day and were 

 so thoroughly mixed, that the fact of the eggs being taken from several 

 females would not in any degree affect the results of the experiment. 

 On their arrival at the campus hatchery the eggs were divided into two 

 lots and placed in separate baskets. These were placed in compartments 

 numbered 2 and 3 in the trough A. An estimation of the number of eggs 

 in each basket, based on measurement, showed that the basket in No. 2 

 contained 3,800 eggs and the one in No. 3 contained 4,520. The basket in 

 No. 3 was covered up so as to exclude almost all light, while that in No. 2 

 was left uncovered and a 60-watt tungsten light was suspended over it at 

 a distance of about one foot from the surface of the water, a cup-shaped 

 reflector directing nearly all the light into the water. 



Observations During Hatching Period 



For a few days previous to hatching it was observed that the em- 

 bryos in the light were much more active than those in the dark. Hatching 

 began November 15 with the water at a temperature of 10.5°C. During 

 the first four days the numbers hatched were quite small in both baskets, 

 but during the next ten days the entire number were hatched. Each day, 

 beginning November 20, the eggs in each basket were measured in order 

 that the number hatched during the previous twenty-four hours could be 

 approximately determined (Table 1). A glance at table 1 shows 

 that the fish in the light hatched more quickly than those in 

 the dark. During the period from November 15 to November 21 



Tabl,e 1. Number of fish hatched each day in light and dark troughs 



IN LIGHT TROUGH 



IN DARK TROUGH 



