26 
DR. DAW ON THE OVA OF THE SALMON, 
the bath and allowed to cool gradually. When next seen, ten hours later, a young 
fish had burst its shell and was vigorous. 
2. An ovum and a young fish were kept in water between 68° and 72° about eight 
hours. The ovum, one of those from the Dee, was then found hatched, and the 
young fish produced was tolerably active. The following day both were exposed 
about nine hours to a temperature between 70° and 80°, rarely reaching 80°. At 
the end of this time they appeared languid, and when in motion disposed to irre- 
gular movements. Removed from the water-bath, on the following day they were 
active, and exhibited no peculiarity appreciable that could be attributed to the higher 
temperature to which they had been subjected. The ovum in its hatching in this 
instance preceded all the others from the Dee, with the exception of the one already 
mentioned, that exposed three days to the open air. 
3. A young fish and an ovum were put into water which in the bath presently 
acquired the temperature of 82°, and in an hour rose to 85°. Now taken out and 
allowed to cool gradually, the circulation in the young fish was found to be very 
languid, the heart contracting feebly. The following day it was found dead. The 
ovum did not appear to suffer materially ; three days after, it was hatched and a 
vigorous young fish was produced. 
4. An ovum kept in water for two hours, at a temperature from 90° to 95°, lost its 
translucency, and opened under water was found to be dead. 
5. An ovum, one of the last from the Dee, kept half an hour in water at 100°, 
afforded the same result. 
6. A young fish was kept in water three hours, the temperature of which at the 
commencement was 70° ; it rose to 85°, and when taken from the bath it had fallen 
to 82°. The heart then was acting with tolerable vigour, and the day following the 
fish appeared to be nearly in its usual state : five days later it was alive and tolerably 
active, but less vigorous than those which had not been so exposed. 
7. A young fish kept in water an hour at 84° was found dead. No action of the 
heart was perceptible nor of any of the muscles when it was taken out. Another young 
fish was put into the water when cold without experiencing any bad effect. This 
trial was made to be certain that the fatal effect was not owing to want of air in the 
water. 
8. A young fish was kept in water rising in temperature from 78° to 81° three hours 
and a half without any permanent bad effect that was appreciable. When taken out 
it appeared torpid, but the heart was acting well. Two days after the fish was as 
active as before. 
9. A young fish, kept two hours in water between 88° and 90°, was, when taken out, 
dead. 
10. A young fish, kept only a few minutes in water at 92°, appeared to be dying 
when taken out ; the circulation in its tail was stopped and the heart was acting feebly ; 
