88 



iiard obscrvc'd tliat when tlio tcmperatui'c of the mai»'- 

 lU'siiini water canic to 0°, tlie Hshes bccanu' little by little 

 iiiHiiotilc; when it rcaehcd -2° and -3°, the complete 

 cessation of motion gave the animals a dead appearance. 

 However, they were not rigid bnt ** perfectly supple." 

 On rewarming, they resumed motion and soon behaved 

 normally. 



Britton (1924) made a somewhat extensive study on 

 the resistance of the skate, sculpiii, sea raven, flounder, 

 eelpouf, cod, foiicod and pollack to sub-zero temperatures. 

 The fishes were immersed in refrigerated tanks containing 

 sea watei-. The effects of cold, as exemplified in the case 

 of the sea raven, were in general, as follows. After an 

 exposure of 30 minutes to - 1.9°, the rectal temperature 

 w^as around - 1° ; the body then became rigid (not by con- 

 gelation but by some cold rigor ; the freezing point of sea 

 water being -1.6°), the respiratory movements, the jaw 

 and tin reflexes and finally the heart-beat ceased. When 

 re warmed, most of these fishes were dead. The lethal 

 body temperature was, then, that produced by an immer- 

 sion of the fish from 20 to 60 minutes in a bath at -1.9°. 

 At higher sub-zero temperatures, the fishes were also 

 usually killed, although after a longer time. Slow and 

 gradual cooling gave the same final result as rapid cool- 

 ing by abrupt immersion. The elasmobranchs were more 

 resistant. 



Kalabuchov (1934) reported that the carp could not be 

 subcooled to temperatures below - 5°. When frozen with- 

 out subcooling, the fishes survived minimum body tem- 

 peratures of -0.2° to -0.5°; they were killed when the 

 latter dropped to -2° to -4.9°. Completely frozen fishes 

 could never be revived. 



Borodin (1934) studied the effects of low temperature 

 on some 10 different kinds of fishes including, among oth- 

 ers, the mummkliog, eel, gold fish, young carp, perch, and 

 mild-minnow. The low temperatures were produced by a 

 Westinghouse household refrigerator within the freezing 

 chambers of which the temperature could be kept constant 



