322 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



tilized, a hatch of 70 or 80 per cent. This will show the value of arti- 

 ficial treatment. 



The reasons why spawn as discharged from the fishery will produce 

 no fish, are at once apparent when we consider the conditions that are 

 absolutely essential for reproduction. The eggs must first be fertilized, 

 and to accomplish this they must be mature and come in contact with 

 milt which is unimpaired in vitality ; and then, to carry them through 

 the long period of incubation, the dead eggs must be removed ; otherwise 

 the confervaceous or " mossy" growth therefrom will spread and destroy 

 them all. Now, the chances of these essential conditions being fulfilled 

 in the case of spawn dumped from the offal barrel, or dropped through 

 the floor of the fishery into the water below, are too small for compu- 

 tation. First, from 75 to 100 per cent of the eggs dressed from the fish 

 are "unripe" — that is, the egg germ is immature and incapable of being 

 fertilized ; second, both males and females are generally dead before the 

 dressing is commenced ; and fertilization is out of the question when ail 

 vitality has departed from the male principle; and, third, granting that 

 25 per cent of the offal spawn is fertilized, which is highly improbable, 

 there would still remain 75 per cent of dead eggs — sufficient to make a 

 rotten mass of the whole batch in a comparatively short time. 



Artificial propagation consists simply in bringing the germ and vital- 

 izing principle together at the proper time, and then protecting the 

 embryo ; and the assistance thus rendered enables us to produce results 

 many times greater than nature can produce. 



North ville, Mich., April 15, 1885. 



MEMORANDUM BY PROFESSOR BAIRD. 



The conditions under which the whitefish develop have been thor- 

 oughly established, both in this country and in Europe. Such acceler- 

 ation of development as that referred to is entirely contrary to the 

 nature of the fish. The small. fish mentioned are probably of quite 

 a number of species, principally the young of minnows and chubs, mixed 

 with a few species that never attain a length of more than a few inches. 

 The drippings from the fish-houses and the discharge of offal into the 

 water in their vicinity would undoubtedly tend in a short time to bring 

 together an immense congregation, a phenomenon which I have myself 

 witnessed many times. 



1 shall be glad, however, to put this question to a careful test by an 

 examination of any specimens that may be collected and sent to me. 

 An ounce of fact is worth a pound of speculation, and whatever may 

 be the probability the question can only be settled positively by 

 observation and experiment. There is not the slightest difficulty in 

 identifying a whitefish, even just from the egg, still less when several 

 inches in length. 



