632 EEPORT OF COMMISSIONER OF FISH AND FISHERIES. 



Experiment 3. 



Placing nearly developed eggs from water having a temperature of 

 12° (53.6^ F.), into water having a temperature of only 1^ to 2^ (33.8°- 

 35-6*^ F.), does not injure them. 



For this experiniGnt eggs were selected whose embryo if left in water 

 having a temperature of 11° to 12° (51.80-53.6° F.) would have been 

 hatched after two days, whilst now, in water having a temperature of 

 only 2° (35.6° F.) they required twelve days. In comparing this result 

 with that of the preceding experiment, it appears that further developed 

 eggs are more retarded by the influence of cold than those whose develop- 

 ment has not advanced quite so far. In the second experiment the 

 hatching was only delayed four to five days in spite of their being ex- 

 posed to cold water for fully three days; whilst in this third exj)eriment 

 they were delayed twelve days, although the eggs were only exposed to 

 the cold for two days. The whole time consumed from impregnation to 

 hatching was, in this experiment, about twenty days. 



Experiment 4. 



Those ^g^fh which immediately upon their arrival at Kiel were placed 

 in water having a temperature of 1° to 2° C. (33.8°-35.6 F.) did not 

 develop as evenly as duriug the first three experiments. 



The first young fish left the eggs on the twenty-eighth day after im- 

 pregnation, the majority between the twenty- ninth and thirty-third day, 

 and a few even later. If we take into consideration, that during the 

 first day these eggs had been in warmer water (8°.4 to 12° ^47.12°- 

 53.6° F.) and that if immediately on being impregnated they had been 

 placed in water having a temperature of 1° to 2° (33.8°-35.6° F.) their 

 develox)ment would have been a few days slower, it may well be supposed 

 that in that case they would have required thirty-three to forty days. 



In my former experiments with autumn-eggs a similar delay occurred 

 at a temperature of 3°.5 C. (38.3° F.). It seems, therefore, that the eggs 

 of the spring fish differ somewhat in this respect from those of the 

 autumn-fish. This difference, however, is not marked enough to draw 

 special conclusions from it. It must be granted that there is a similar 

 delay caused by cold in both cases. 



Experiment 5. 



The period of development was by this experiment shown to increase 

 in length if still colder water was applied. At first, water was used 

 having a temperature of 0° (32° F.) ; with this temperature, the first 

 young fish were not hatched till the forty-seventh day, and if we count 

 in the fii^st day spent in warmer water, still later. 



The young fish, however, did not seem to be quite healthy, although 

 some of them swam about for days in a lively manner. Many retained 

 a verv noticeable deformity of the back. It could not be ascertained 



