1885.] on the Mechanical Production of Cold, &c, 313 



Still, when such a mass — say a piece of muscle — is thawed, its micro- 

 scopical structure seems to be unaltered. All that can be said is that 

 it is moister than ordinary fresh muscle. It is probable, therefore, 

 that the bodies of micro-organisms are also frozen solid, and yet 

 they apparently may live for a long time in this condition. One 

 cannot suppose that in these circumstances any of the phenomena of 

 life take place ; the mechanism is simply arrested, and vital changes 

 may again occur when the conditions of a suitable temperature 

 return. Such considerations led the lecturers to examine whether 

 any of the vital phenomena of higher animals might be retained at 

 such low temperatures. It was ascertained that a live frog may be 

 frozen quite solid throughout at a temperature of from ~ 20° F. to 

 — 30^ F. in about half an hour. On thawing slowly, in two instances, 

 the animal completely recovered. When kept in the cold chamber 

 longer than half an hour, the animal did not recover, but the 

 muscles and nerves were still irritable to electricity, responding to 

 weak induction shocks. Keflex action, however, was abolished. In 

 two cases, frogs were exposed for twenty minutes to a temperature 

 of — 100^ F. On thawing, they did not recover, but the muscles 

 still feebly responded to electrical stimulation, showing that their 

 irritability had not disappeared. The probability is that longer 

 exposure to this temperature, or exposure for a shorter time to a 

 lower temperature, would destroy muscular and nervous irritability, 

 but it is a striking fact that irritability can survive to any degree a 

 transition through a state of solidity produced by cold.* 



16. One experiment was performed on a warm-blooded animal — 

 a rabbit. Before the experiment, the temperature of the rectum 

 was 99 "2° F., pulse 160 per minute, respirations about 45 per minute. 

 At 10 '80 A.M. it was placed in the cold chamber, the thermometer 

 of which stood at — 93^ F. At 11 a.m. it was removed for a minute 

 or two ; it did not seem to be affected, but the temperature of the 

 rectum was now 94 • 2^, a fall of 5° in half an hour. It was then re- 

 introduced into the cold chamber, the temperature of which was read 

 off at — 100^ F. It was taken out at 12 noon ; it seemed to be 

 comatose ; reflex action was abolished ; there were jerking movements 

 of the limbs ; its rectal temperature was now 43^ F., a fall of 51° 

 during the hour ; its pulse was 40 per minute, being a fall of 120 ; 

 and its respirations were barely perceptible. It was placed in a warm 

 place, and it began slowly to recover. In fifteen minutes its tem- 

 perature had risen to 72° F., in ten minutes more to 89° F. Its 

 pulse beats when removed from the chamber were 40 per minute, in 

 fifteen minutes they had risen to 60 per minute, and in fifteen 

 minutes more to 100 per minute. The animal completely recovered. 

 When removed from the chamber at 12 noon, although reflex action 



* Kuhne observed that a frozen frog's muscle will contract after thawing, but 

 the temperatures he reached were not low. 



