PROGRESS IN BIOLOGICAL INQUIRIES, 1926 677 
edge of vitamins has been gained from a multitude of experiments no more 
complicated than this. The work with fish enjoys certain advantages and 
suffers certain handicaps, in comparison with the vitamin investigations in 
higher animals. From a statistical standpoint, the results gained from ex- 
periment with a lot of 1,000 fish are worth more than those gained from a 
single individual or 5 or 10 rats or pigeons. At the same time, the vitamin 
investigators have a “standard rat” to work with, as well as uniform speci- 
mens of pigeons, ete., and they exercise almost complete control over the 
environmental conditions in which their animals exist. There is no such 
thing as a “standard trout,’ and the great fluctuation in the growth rate of 
fingerlings, the frequency and severity of epidemics, the changes in water 
conditions, the cannibalism, the inability to keep an accurate check on food 
consumption, combine to furnish the fish dietitian with food for thought for his 
idle moments. 
Concerning the subject of fish breeding, I can offer little more than a pros- 
pectus at present. Briefly, this is merely the application of the universally 
known principles of selection of parent stock for desirable qualities, such as 
man practices wherever he is rearing animal or vegetable life for his use. 
Strangly enough, application of these simple principles has been merely rudi- 
mentary. At all hatcheries there has been, consciously or unconsciously, a 
selection of the future brood stock from the better grade of breeders, but the 
practice has been spasmodic, applied to large groups chiefly, little accurate check 
of results has been kept, and selection for specific qualities has been largely 
ignored. The commercial dealers probably have accomplished the most in 
this field, and while their efforts and achievements have been commendable, 
the need for immediate monetary profits necessarily has circumscribed their 
efforts. 
We have been forestalled, in our plans to inaugurate a program of scientific 
selective breeding, by an undertaking at the New Jersey State hatchery. 
Doctor Embody, of Cornell University, is directing this project. Briefly, they 
now have a fourth generation of selected brook trout. The original stock 
consisted of survivors from a large number of hatchery fish that had been sub- 
jected to all the vicissitudes of ordinary hatchery life, including a serious 
epidemic. Enough remained to permit the work to proceed on a similar basis 
for the succeeding generations. Summarized, they have cut down the mor- 
tality, at the July fingerling stage, from 98 per cent to 380.8 per cent in the 
1925 generation. At the same time, the average length at this age has in- 
creased from 2 to 3% to 4 inches. Thus, the primary selection was exclu- 
sively for disease-resisting characters, and this has been adhered to through- 
out, aithough rapid growth has entered into the selection from the later gener- 
ations as a secondary character. This has been accomplished by what is 
really mass selection with no attention paid to individual qualities. Inci- 
dentally, I know of no publication, save the report of this work, that treats 
of the selective breeding of trout, except in a cursory way, and that sets forth 
a definite program and describes the results of that program in a definite, 
reliable, and comparable manner, 
As stated, efforts in this field at the Holden station are chiefly aspiration. 
This fall we took eggs from a lot of brook trout that have shown rapid 
growth and early sexual maturity. This is the first yield of eggs from these 
fish, and we will be in position soon to determine whether this precocity has a 
definite influence on the vitality of the eggs or fry. This has been mass selec- 
tion, as the early-maturing character was common to all the fish that spawned, 
and no other outstanding differences existed. We also have one lot of this 
year’s fingerlings, which exhibits the disease-resisting character to a greater 
degree than does the general hatchery stock. These probably will not yield 
eggs in any quantity until 1928. There is also on hand a lot of this year’s 
fingerlings, which has exhibited splendid growth, and these will be depended 
upon as parents of a strain that emphasizes this quality. As for individual 
selection, we have this year taken eggs from five or six females that showed 
desirable qualities in the way of color, form, and production of a large 
number of eggs. These eggs will be segregated, of course, and the lots will 
continue to be handled thus until maturity. The fish spawned from individ- 
ually selected stock are marked by numbered tags for future recognition, and 
the best males are selected for pairing with these fish whenever enough of the 
latter are ripe. However, extensive attempts to establish pedigreed stock will 
be deferred until the general strains have become well established. 
