^Inicricaii I'isltcrics Sucuiy. 107 



About 500.000 eggs were hatched at tlic liozcinan Station, and 

 3.1 least 50 per cent, of the fry arc ahve, and nicjst of thcni arc 

 feeding. 



In stripping the female grayling, the eggs arc a little harder 

 to start, but are then extruded more freely than in the case of the 

 trout. About 3,000 eggs is the average for a fish of twelve inches 

 in length. The eggs are white and as clear as a crystal; they arc 

 smaller than the native trout (S. mykiss) eggs, but after iin[)regna- 

 tion and the absorption of water will average one-seventh cjf an 

 inch in diameter, while the native trout eggs are one-sixth of an 

 inch, and the brook trout (S. fontinalis) eggs arc one-fifth of an 

 inch in diameter. 



Soon after fertilization the eggs l)ccome glutinous and ad- 

 hesive, forming bunches or masses of various sizes, when fungus 

 rapidly develops and kills the egg. This renders the work of 

 picking laborious but imperative. The embr}o develops rapidly. 

 and is in constant motion, often causing the egg to roll over on 

 the tray. The grayling eggs are lighter than trout eggs, almost 

 semi-buoyant, and from our experience would be better hatched 

 under a pressure of water from below. In an improvised jar the\- 

 did well, and the bunching and development of fungus did not 

 occur. Perhaps the method followed with pike-perch eggs in 

 using starch or muck might cause the eggs to separate, and the 

 bunching be prevented. .\'e.\t season I propose to experiment 

 with fine (piick-sand. so-called, which is abundant about Red 

 Rock Lake; it is more like tine marl, as tine as wheat tiour. 



The embryo begins to show life and motion before the eye- 

 sj)ots are visible. The eye-spots are small gilt specks, with a 

 mimUe Ijlack ])upil.'and ap])ear in from three to five days. The 

 period of incubation is from 10 to 12 davs, at a temperature of 

 about 50 degrees. The fr\ are hatched with a very small yolk- 

 sac, about half the size of the egg, and w liicli is absorbed in about 

 a week, when the fry immediately l)ecoiues a free-swimming ani- 

 mal, about one-half an incli in length, and is cjuite slender and 

 delicate. The}- do not begin to feed so readily as trout, and re- 

 quire constant coaxing, as often as every half hour, with liver 

 as finely divided as ])ossible. being in fact bloody water. The 

 l)cst method of feeding and rearing is yet to be determined. Those 

 liatched and planted in VAk Creek did well, being double the size, 

 at the same age, of those hatched at Hozeman Station, which 

 proves that we must follow, as closely as possible, the natural con- 

 ditions of breeding. 



The gravling does best in sand\- and i-raxelK- streaius, with 



