BULLETIN OF THE UNITED STATES FISH COMMISSION. 203 
50.-SELF-BEPK0DUCING FOOD FOSS YOUNG FISH. 
My FEABiK SI* MASON, CONSUL,. 
Every person wlio has been interested in the artificial propagation 
[; of fish, and particularly trout and the several other species belonging 
to the genus Salmo , knows what care and labor are necessary to carry 
the young fry through the period immediately following the absorption 
J of the umbilical sac, and to bring them to such a stage of maturity 
that they can be safely turned loose in open ponds or streams to shift 
for themselves. The mere hatching of the eggs involves no difficulty, 
and, under fair conditions, is ordinarily so successful as to make the 
propagation of fish in almost any quantity an apparently easy matter. 
But with the commencement of artificial nutrition the serious part of 
the task begins, arid it is usually a small percentage of the swarms 
which are hatched that reach the maturity of yearlings, at which pe- 
riod the dangers of infancy are past. During the intervening months 
it has been customary to feed the young alewives on curdled milk, co- 
agulated blood, finely hashed meat and liver, grated yolk of eggs, mac- 
erated brains of animals, etc., the preparation of which, and the fre- 
quent feeding of the dainty little creatures, involves constant and more 
or less costly labor. Moreover, none of these forms of nutriment have 
been found entirely satisfactory, for the reason that they are all dis- 
tinctly artificial and different from the living, organic food which na- 
ture provides for those species of fish during their tender, infantile 
period. The difficulty of providing proper nutriment results often in 
turning out the young fry into open water too early, when the temper- 
ature of the stream or pond is so much below that of the tanks in 
which they have been hatched that they perish by thousands from chill 
and inanition, without making an effort to find natural food in their 
new element. Accordingly the problem has been to devise a natural, 
self-reproducing food, so easy and certain in preparation that it may 
be cheaply and abundantly provided, and thus facilitate the mainte- 
nance of the alewives during the first ten or twelve months of their ex- 
istence, by the end of which rime they should be so strong and active 
that a large majority may be relied upon to survive the struggle for 
life in larger waters. 
The result seems to have been fully attained by a discovery made 
several years ago by Mr. F. Lugrin, of Geneva, and practiced since 1884 
in the piscicultural establishment at Gremaz, in the department of Ain, 
in eastern France. As this process has been examined and approved 
by eminent experts, sent specially for the purpose by piscicultural 
societies of England and other countries, it is thought that some ac- 
count of it may be of interest to the large and rapidly growingclass of 
fish-culturists in the United States. 
