BULLETIN OF THE UNITED STATES FISH COMMISSION. 143 



sington selected certain fishes for experimentalizing as to what tem- 

 peratures they could survive in. All were first deposited in water reg- 

 istering 53°, which was gradually increased by the infusion of hot water 

 through a tube, which caused the temperature to rise steadily. The 

 rapidity of this rise is not given. We are told that none of the tish ex- 

 hibited signs of failing vitality until the thermometer recorded 82°, when 

 a perch became prostrated, and shortly afterwards its congeners fol- 

 lowed its example in rapid succession in the following order : Roach, 

 *2A°; salmon, 83°; minnow, 85°; gudgeon, 85£°; dace, 86°; tench, 88° ; 

 carp, 91°. Brandy is stated to have restored them all except the dace, 

 which died. Whether further notes of these fishes have been kept, and 

 it any more have succumbed, it would be interesting to know ; but none 

 of the temperatures appears to have reached what is normal for fish in 

 India at certain seasons. 



Dr. John Davy in 1853 made some very interesting observations on 

 the above subject of temperature on ova and young fish, in each instance 

 the experiment being carried on in a thin glass vessel of the capacity 

 of about four ounces, nearly full of water, and this vessel was placed in 

 a water bath of the temperature required. An ovum was two and a 

 halt hours in water at 70°, which rendered its circulation languid; kept 

 two hours more, and increasing the heat of the water to 80°, no further 

 apparent ill effects were seen. The vessel was now removed from the 

 bath and allowed to cool gradually, and ten hours later a vigorous 

 young fish was found to have burst its shell. An ovum and a young 

 fish were kept in water between 68° and 72° for about eight hours, 

 wheu the agg was found to be hatched and a tolerably active young 

 tish was produced. Next day both were exposed to a temperature 

 between 70° and 80°, rarely reaching 80°, and at the end of the day 

 they were languid, or, if in motion, disposed to irregular movements. 

 Removed from the water bath, the next day they were active, and sub- 

 sequently showed no ill effects from their treatment. A young fish and 

 au ovum were put into water raised to 82°, and after an hour to 85°, 

 when the water was gradually cooled ; but the circulation in the young 

 fish was found to be languid, and the following day it was dead. The 

 agg did not suffer materially for three days; subsequently a vigorous 

 young fish was produced. An ovum kept in water for two hours at 

 from 90? to 95° died, as did also one put for half an hour in water at 

 10()O 



A young fish was kept three hours in water, commencing at 70° and 

 gradually increased to 85°. The heart was then acting with tolerable 

 vigor, and the following day the fish appeared to be nearly in its usual 

 state, and five days subsequently it was tolerably active. A young 

 fish kept in water at 84° was found to be dead, and to be sure that the 

 result was not owing to a want of air in the water the experiment was 

 repeated in the same water when cold, without injurious results. Another 

 young fish was kept in water three hours and a half, rising from 78° 



