[7] OPERATIONS AT NORTHVILLE AND ALPENA. 819 



days. The fry were treated tlie same as our native trout, but did not 

 eat so readily at first, about one-fourth of them dying soon after the 

 absorption of the umbilical sac, the most critical period of trout rais- 

 ing. Such, however, as commenced at once to take food have done very 

 well, indeed, and are at the present writing (September 1) quite as 

 large as the native trout of the same age. 



RAINBOW TROUT. 



In this connection I am compelled to record the first serious failure 

 in the history of the Northville establishment. Our facilities being first- 

 class, and having been uniformly successful in the propagation of trout, 

 not excepting the preliminary experiments with rainbow trout for four 

 seasons, I had confidently expected to embryonize from one to two 

 hundred thousand eggs from the stock of irideus hatched and grown at 

 this station; but we succeeded in getting only about 45,000 eggs 

 (many of the females failing to mature their spawn), and in fertilizing 

 but 15 per cent, of these, resulting in a hatch of G,400 fish. The parent 

 fish of both sexes were, and still are, perfectly normal, so far as conduct 

 and aj)pearances would indicate. The trouble, however, seems to have 

 been entirely with the females, as the quantity and quality of the male 

 principle was all that could be desired. Whatever the cause of the difS- 

 culty the effect was at once apparent in the abnormal character of the 

 fluid surrounding the eggs. From most of the females the eggs would 

 fall into the receiving pan like shot, accompanied by ^ to 1 fluid ounce 

 of a watery substance, sufficient of which had been absorbed to pre- 

 vent fertilization. If there was any doubt that absorption of water by 

 a large percentage of the eggs had taken place before leaving the fish, 

 it was dispelled by the fact that they were quite full and hard when 

 taken and refused afterwards to take up more water. Moreover, the 

 eggs from six females were found enveloped in the natural viscous fluid, 

 and these were successfully fecundated. 



Without attempting to account for the failure, I am inclined to think 

 that the fish were overfed, and that the inflow to their pond gave them 

 a current quite too slow and feeble, resulting for the most part in great 

 inactivity and in their being in good condition for market at spawning 

 time. As an experiment I propose to reduce their food allowance to 

 the minimum, and i)lace them in a good current of water in one of the 

 long, narrow ponds lately constructed, the irideus being j^articularly 

 fond of rajjids and swift currents. 



In appearance these eggs were almost identical with those of the sal- 

 velinusj being about the same size and fully as light colored. Though 

 the most of them were a total loss, those that were fertilized produced 

 exceedingly vigorous fry, which have since grown so rapidly that they 

 are now larger than any of the species of same age heretofore grown at 

 the batch ery. 



The following table may be of value as showing the time of spawn- 



