i44 BULLETIN OP THE UNITED STATES FISH COMMISSION. 



to 91°, without bad effects, while another two hours and a half in water 

 between .88° and 90° died. One kept a few minutes in water at 92° 

 seemed to be dying when removed, and appears to have died in about 

 a quarter of an hour. Another was kept three hours in water gradually 

 rising from 78° to 88°. At 85° the heart was acting, but no circulation 

 was perceptible in the tail ; at 88° it died. Dr. Davy has recorded 

 many other experiments on this subject, as well as on the degree of 

 temperature fatal to fishes. 



In August, 1882, he placed a common trout of about a quarter of a 

 pound weight into a good volume of water at 62°, which was pretty 

 rapidly raised to 75° by additions of warm water, when it became very 

 active and tried to leap out. In an hour the temperature was increased 

 to 80°, and after a few more minutes to 85°, when it became convulsed, 

 and, although transferred to cool water, died. When the water had sunk 

 to 70°, smaller trout and a minnow were put in, and although the 

 next morning the temperature had sunk to 67°, the trout was dead, but 

 the minnow had not suffered. 



A parr of the salmon was similarly treated, the water in half an hour 

 being raised from 60° to 70°, and now it tried to escape. The water 

 was raised to 80°, and it became torpid and convulsed ; at 84° it seems 

 to have died. 



A char of about the same size had the water gradually raised to 80°, 

 when it seems to have died. The trout tried to escape by leaping out of 

 the water, while the char kept to the bottom, with its head downwards, 

 as if seeking for a cooler locality. A small perch was put into water at 

 83°, falling in fifty minutes to 80° ; after two hours it was found dead. 



A minnow was put into water at 92°, and in less than two minutes it 

 had turned on its side; but the water falling to 90°, it recovered, resum- 

 ing its natural mode of swimming. A gold carp was put into water at 

 96°, but at once became restless. After a few minutes the temperature 

 had fallen to 94°, and it remained motionless; now transferred to water 

 at 70°, it rapidly revived. After about an hour it was placed in water 

 at 93°, which at first it bore with, then became languid ; but as the water 

 cooled it revived, and <*t 88° it resumed its natural position. 



A common carp was placed in water at 60°, raised in five minutes to 

 78°, and in twelve more to 80° ; after another half hour the heat was 

 suddenly increased to 85°, but it became languid, so it was allowed to 

 cool to 80°, when it seemed to revive, so the heat was increased to 95°, 

 and as it appeared as if dead, it was lifted into cool water, where it slowly 

 recovered its powers. Other similar experiments on the loach and the 

 eel were made. 



Cheltenham, England, February , 1885. 



