314 M)\ Coleman and Prof. McKenclrich [May 29, 



was abolished, the muscles were still irritable to electrical stimula- 

 tion, and on placing the wires over the sciatic nerve without cutting 

 the skin, strong spasms of the muscles of the leg were caused, showing 

 that the nerve was still irritable. It follows, therefore, that some 

 of the effects of the extreme cold were due to inactivity of the nerve 

 centres. Consciousness and reflex action were abolished, owing to 

 inactivity of the grey matter of the encephalon and of the spinal 

 cord. 



The effect of the extreme cold on the warm-blooded or homoio- 

 thermal animal, as contrasted with its effect on the cold-blooded or 

 poikilothermal animal, is very striking. The cold-blooded frog 

 became as hard as a stone in from ten to twenty minutes, and the 

 temperature of its body was probably the mean temperature of the 

 chamber ; the warm-blooded animal produced in itself so much heat 

 as enabled it to remain soft and comparatively warm during exposure 

 of an hour's duration to — 100° F. Still its production of heat 

 was unequal to make good the loss, and every instant it was losing 

 ground, until, at the end of the hour, its bodily temperature had fallen 

 about 56° F. below its natural temperature. Had it been left in 

 the chamber long enough, its bodily temperature would have fallen 

 until it reached the temperature of the cold chamber, and it would 

 then have become as hard as the frozen frog. It is remarkable, how- 

 ever, that even at the end of an hour's exposure to — 100° F., its 

 bodily temperature was 143° above — 100° F. As blood freezes and 

 the haemoglobin crystallizes at about 25° F., had the temperature of 

 the body fallen below that point, the animal would not have re- 

 covered, as its blood would have been destroyed. 



The lecturer observed that several researches had been made, prior 

 to those of himself and Professor McKendrick on the influence of 

 cold, none of them, however, very decisive as regards the microphytes 

 concerned in the putrefactive processes. Thus, before 1872, we find 

 Dr. Ferdinand Cohn ^ stating that he had subjected bacteria to low 

 temperatures without destroying their activity. He gives the 

 temperatures as follows : — Exposure for 12 hours 30 minutes to a 

 temperature 0° C. ; for Ih. 30m. to- 16° C. ; for Ih. 45m. to 

 - 17° C. ; for 3h. 30m. to - 18° C. ; for 4h. 30m. to - 18° C. ; for 5h. 

 to - 17-5° C. ; for 6h. to - 14° C. ; and for 7h. 30m. to - 9° C. He 

 produced the cold by freezing mixtures, and the lowest temperature 

 he obtained was - 18° C. = 0° F. In 1870-71, M.Melsens exposed 

 yeast and vaccine lymph to very low temperatures ( — 78° C), by means 

 of solid carbonic acid, without destroying the power of fermentation 

 or inoculation.f 



Klein J states that " Freezing destroys likewise most bacteria, 



* Cohn's Beitrage zur Biologie der Pflanzcn, 1870, Zweites Heft, p. 221. 

 t Melsens, Comptes Rendus, Todjg Ixx., 1870, p. G20 ; also Coniptes Rendus, 

 Tome Ixxi., p. 325. 



X Klein, Micro-organisms, p. 35. 



