CO 



luiiKt Iciii jxn'di'Ki ;iii(l Itdi/d riridis) was lowered slowly, 

 the stimulus eoudueliou dropped im})ereeptil)ly down to a 

 certain ])oiii1 (a ))lieiiomeuoii not due to cold), then it sank 

 suddciilx lo a \ci>- small \alue, and finally it dropped 

 slowly auaiii 1<> coinplcle disappearance. The "critical 

 1emi)erature" a1 which the sudden drop occurred was 

 found to be between - 2 and - 10. With a thermocouple 

 inserted in the nerve it Avas possible to observe a remark- 

 able temperature rise coincident with the decrease in con- 

 duct ion. Kvidently the tissue was then freezing. Upon 

 warming, a slight conduction reappeared sometimes, 

 either below or above the freezing ])()int; the original con- 

 duction, however, was never reached again; and some 

 nerves did not recover at all. When there w^as a return 

 of conduction, it took place between - 11° and 7°. With a 

 too sudden cooling, convulsive twitches, due to stimula- 

 tion by cold, disturbed the experiments. 



In 1932, Bahrmann repeated Biihler's experiments on 

 the same material, but he determined the electrical con- 

 ductivity of the nerve simultaneously with the stimulus 

 conduction at decreasing temperatures. He found that 

 there was a gradual increase in resistance and decrease 

 in stimulus conduction as the temperature was slowly 

 lowered down to about -6.4° to -7°, at which tempera- 

 ture there occurred abruptly a large rise in resistance and 

 simultaneously an abrupt drop in stimulus conduction, 

 followed by the absolute cessation of the latter. Thaw- 

 ing, as judged by the change in resistance, occurred be- 

 tween - 1.5° and 0°. Upon warming, stimulus conduction 

 w^as never resumed below - 1.8° and often it was not re- 

 sumed at all. As a whole, Bahrmann 's experiments 

 would show that death or serious injury results from 

 freezini>- after a subcooling of about 6°. 



Summary: 1. Most of the tissues studied in this sec- 

 tion: plant epidermises, juicy tissue from leaves, stems 

 or roots, embi-yonic animal tissues, ciliated epithelium, 

 muscular tissue and apparently also nerve tissue, are 



