Dead Ova

The following is taken from the Ohio Report on fisheries, as it expresses our views on the possibilities and limits of impregnating the eggs of dead fish:

An opinion has long been prevalent that the roe or ova of a dead female fish could be fertilized by milt taken from a dead male fish; in other words, it was firmly believed that the ova taken from the dead fish, as they were opened and the entrails removed at the fish packing-houses in Sandusky, became fertilized by the milt from dead males when their entrails were removed and all cast into a common heap as offal, mingling with the ova of the females, and that then and there the ova became as thoroughly fertilized or impregnated as if both the fish were alive. Many otherwise intelligent and well-informed persons very freely asserted that during the winter months thousands of millions of young whitefish "just out of the egg " were to be seen around about the wharves of the packing-houses in Sandusky bay.

Believing it to be of the utmost importance in artificial reproduction of fishes to know with absolute certainty whether the ova of a dead fish can be fertilized, Mr. Charles Carpenter, of Kelley's Island, was instructed to institute a series of experiments to determine this matter beyond any peradventure. He was instructed to obtain both the milt and ova of fishes dead one hour and those dead several hours, and subject them to the process of fertilization ; then with the milt of the dead male to fertilize the ova of a live female ; then with the milt of the live male to fertilize the ova of a dead female; finally, to preserve the milt of a live fish and fertilize ova directly after extrusion, with the milt, after it had been taken six, twelve, eighteen, to twenty-four hours from the male.

The results of the fertilizing experiments is to the effect that immediately after the death of the fish, male or female, the ova, under favorable circumstances, can be fertilized; that the milt can be preserved some hours without losing all its fertilizing power; that milt of fish within an hour after its death will fertilize almost as well as that taken from a live fish. These experiments were made with whitefish (coregonus alba) milt and ova - those of other species may differ widely in susceptibility of impregnation or fertilization after the death of the parent Statements are made that milt of the trout kind has been shipped from California to Boston without parting with its fertilizing influence entirely.

Mr. Carpenter learned, furthermore, that when a single drop or two of milt was all that could be obtained, and it appeared thickish, that the fish was about exhausted and such milt contained con-paratively few spermatozoa - hence it was almost worthless for the purpose for which it was intended. But when the milt was in considerable quantity and was very fluid, then it contained comparatively the maximum quantity of spermatozoa, and a single drop of it would fertilize more ova than twenty drops of the thick. Both milt and ova were entirely worthless if exposed to a temperature below 31°. This degree of temperature appears to deprive the milt of its fertilizing influences, and deadens the susceptability of the ova of being fertilized.

Many statements are made by fishermen and others to the effect that the eggs of fishes are often found frozen in ice on the shore or banks of streams, as well as ponds and lakes, and afterwards hatched successfully.

Some experiments, carefully conducted by Mr. Carpenter, demonstrate that whenever the eggs are subjected to a temperature below 32° Fahrenheit, that vitality ceases.

Statements have been found going the rounds of the press, to the effect that fish have been found in the streams, frozen stiff, and afterwards restored to life. All experiments made in this direction have resulted in the absolute death of the subjects of the experiments. Experiments made by us in fertilizing eggs after they were extruded, resulted in showing that where five minutes were allowed to elapse after the eggs were obtained, and before the milt was applied, only four per cent. were impregnated, and of all those that were left a longer time none were impregnated.