1128 EEPORT OF COMMISSIONER OF FISH AND FISHERIES. [2] 



them and then withdrawing it through the same opening the neces- 

 sary change of water could be effected. In order, however, to accom- 

 plish this alternate influx and eftiux of the water conveuientl}-, it was 

 necessary to make use of some automatic device, so that the work 

 could go on Mithout the continual supervision of some expert. The 

 method by which this was efl:ected is shown in the accompanying 

 sketch. 



Apparatus for hatching buoyant fibh eggs. 



In all of the various forms of apparatus that were used at different 

 times during the season, a certain percentage of eggs was hatched, wbere 

 no accident intervened to terminate the experiment abruptly. The per- 

 centage of loss, however, was very large — much larger than could be 

 tolerated> in any method where practical results in hatching were to be 

 looked for. These losses were to be attributed mainlj- to two causes: 

 the increase in the density of the eggs as incubation went on by the 

 accumulation of sediment, and the inferior density of the water em- 

 ployed as compared with sea water. Could these methods have been 

 used where water of the density of the sea was available, and where 

 perfect means of filtration could be provided, I have no doubt but that 

 all the forms of apparatus used would have given good results in hatch- 

 ing- 



The largest percentage of hatching was attained in the upright glass 

 funnels, in which the eggs, twice a day, were thoroughly washed by a 

 jet of water, the effect being, by the attrition of the eggs upon each 

 other, to keep the surfaces perfectly clean and to maintain their buoy- 

 ancy. The percentage of hatching in the majority of the cases was very 

 small, not more than from 5 per cent, to 15 per cent, of the total number 

 of eggs employed. In one experiment with a glass funnel, containing 

 40,000 eggs, the water in which, from its location near the stove, was 

 uniformly several degrees higher in temperature than the water in the 



