[3J 



OPERATIONS AT CENTRAL STATION. 



1019 



(a) Carelessness in handling the eggs resulting in imperfect impreg- 

 nation. 



(b) The forwarding of unimpregnated water-hard eggs under the 

 impression that they were impregnated. 



(c) The low temperatures of water prevailing during the season, which 

 made impregnation very difficult in the hands of unskilful or careless 

 spawn-takers. 



The following summary (Table 1) shows the sources from which the 

 eggs were obtained, and the quality of the eggs in each case, as indicated 

 by the percentage of loss in transportation and hatching. 



Table I. — Summary of shad eggs received at Central Station, season of 1883. 



Table II furnishes as complete a history of each lot of eggs received 

 at the station as it was practicable to obtain, but some of the records 

 lack the precision necessary to furnish the data for satisfactory con- 

 clusions. It is evident, from the table, that in general the period of 

 incubation varies inversely to the temperature prevailing during the 

 incubation. But we cannot disguise the fact that there are other in- 

 fluences not well understood which accelerate or retard development 

 under precisely the same conditions of temperature. We know, for 

 example, that strong light, whether direct or diffused, will accelerate 

 development; again we know that continuous dark and cloudy days 

 will retard development under precisely the same conditions of water 

 temperature. It is possible, too, that the rate of development may be 

 in a measure determined by the initial temperature, or that prevailing 

 at the time of impregnation. It will require careful observations for 

 several seasons to obtain the data necessary to discuss the conditions 

 influencing development, and Table II is published here in order to put 

 on record, in convenient form for reference, such data bearing on the 

 question of development as have been accumulated. 



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