372 FISHING IN AMERICAN WATERS. 



and Gadidce, which appear as infinitesimal atoms of albumen, 

 enlarging tenfold within an hour after impregnation, turning 

 entirely white, and the fish is hatched in a less number of 

 hours than it takes of days for the genus Salmo. Incubation 

 with all the salmon families is slow, the egg indicating no 

 appreciable increase in size by fructification ; but, being por- 

 ous, with tubes and globules, scientifically termed micropyles, 

 the milt fills them, and they present the appearance of white 

 globules in the egg, as represented by Fig. 1, and enlarged 

 like Fig. 2. After the egg has remained in running spring 



Tig. 1. Salmon egg of natural size after fecundation. Fig. 2. Salmon egg enlarged, to 

 show the vesicles and globules. Fig. 3. Salmon egg in which the embryo is per- 

 ceptible. Fig. 4. Alevin just hatched, enlarged, and showing the umbilical vesicle. 

 Fig. 5. Natural length of the alevin. 



water of temperatures ranging from 40 to 50, the egg will 

 disclose the shape of the embryo salmon in from fifty to sev- 

 enty days,* as illustrated by Fig. 3. After the embryo be- 

 comes perceptible, and the eyes tolerably distinct, within a 

 few days say from five to fifteen the salmon will hatch 

 into the shape of Fig. 4, as enlarged from the natural size, in- 

 dicated by the length of line, Fig. 5. Suspended to the um- 

 bilical cord is a sac containing aliment for the alevin, on 

 which it subsists by absorption from twenty-five to forty 

 days, when the tiny creature takes its second form. The egg, 



* Salmon have been hatched in fifty-five days, and trout in thirty-five days, 

 in water 55 ; but Mr. Francis recommends spring water of from 40 to 45, 

 while the Cold Spring trout-ponds at Charleston, N. H., are excellent hatch- 

 ing-waters, and they are said to be 60 as mean temperature. 



