Auicrican Fisheries Society. 73 



practically the saiiic nunihcr. Tho (lucstion of a^e. then, does 

 not enter in as a disturbing element. 



3. It may be that the variations tabulated are the result of 

 environmental conditions expressed upon the fry and younp; ; 

 they may be merely accpiired characters of ciuestionable hered- 

 itary value. In other words, it may be that the fry reared at 

 WockIs Hole attain to a larger number of fin-rays than the same 

 fry would possess were they reared at Waquoit. While certain 

 experiments that the writer has made induce him to believe that 

 these variations in the number of dorsal lin-rays are really deep- 

 seated characters and are iioi the result of environmental condi- 

 tions, it must be remembered that if the variations are admitted 

 to be the result of strange surroundings, the method is not 

 necessarily thereby vitiated, for if it is insisted that certain ex- 

 ternal influences may afifect the fry after liberation from the 

 hatchery, and the results of these influences are expressed by 

 a change in the fin-ray formula, it must also be equally true 

 that the much more extreme an unusual environmental condi- 

 tions imposed upon the still younger organism while Tcitliiii 

 the hatchery will also leave their stamp, and the artificially 

 hatched fish will thus present some peculiarity (acquired though U 

 may be) which will be brought out by the plotting of curves of 

 distribution. 



Mr. Whitaker: What is your opinion. Prof. Birge, as to these 

 structural differences spoken of and the ideas advanced in this 

 paper upon that point? 



Prof. Birge; It seems to me there is a chance for very val- 

 uable work just in this connection. The flatfish hav an enor- 

 mous number of fin rays, so great a number that we should 

 naturally expect the kind of local variation which the jirofessor 

 finds. Whether this would be true of the whitefish or lake 

 trout or any of the fish of the Great Lakes, I dont' know, but it 

 seems to mc that there is a point the fish culturists might well 

 investigate. I haven't very much doubt that somewhere or other 

 there could be found some such difference between the Lake 

 Michigan lake trout and the Lake vSuperior lake trout. If, as 

 Mr. Nevin says, we have to go to raising Lake Michigan trout 

 eggs and planting them in Lake Superior, it would be (|uite 

 possible to determine whether the fish as they are caught were 

 the residt of planting or the result of natural increase. 



It is almost always true with any species of animals from 

 different localities, certainly when they are widely separated, that 



