58 



sertcd into tlic middle of it. Isolated imisclcs lliiis 1 fcated 

 could be frozen and sid)jec'led lo a temperature of -2.9° 

 Avitliout losing- tlieir in'i1al)ility completely. The death 

 point would then lie at about - 3°. 



In another sei'ies of experiments by the same author, 

 determinations were made on the frofi muscles in situ, for 

 which purpose the frog's leg- was pulled through a small 

 glass tube, as before, the frog being meanwhile fastened 

 to prevent movement. The muscle, not cut off from the 

 circulation by any ligature, was still irritable after hav- 

 ing been frozen to -4.06°. Its death point is given as 

 lying at about -4.1° to -4.2°. 



Moran (1929) exposed to freezing temperatures excised 

 frog's muscles (sartorius and gastrocnemius) in constant 

 temperature rooms and, after freezing and thawing, he 

 tested the vitality of these muscles by observing their 

 response to an electric stimulus, their osmotic properties 

 and also their electric resistance. Cooling was very slow, 

 a long time being allowed for the establishment of the 

 temperature equilibrium. In a previous determination, 

 the freezing point of the material was found to be -0.42°. 

 Moran 's results can be summarized in the following 

 points : 1. The muscles brought to temperatures below 

 - 2° were killed ; 2. The muscles frozen hard but exposed 

 to temperatures above -2° for less than a day could be 

 revived after thawing; 3. The muscles left for a long time 

 in the frozen condition above the critical temperature of 

 -2° were killed; the lethal time of exposure was about 

 7 days at - 0.9°, 4 days at - 1.5° and 20 hours at - 2°. In 

 his attempts at rapid freezing, by immersion in liquid air 

 for example, Moran could never ol)tain revival. He thinks 

 that at the ci'itical point an irreversible change takes 

 place in an inappreciable time. 



Chambers and Hale (1932) reinvestigated the problem 

 of the death temperature of isolated muscles, using some 

 of the methods that C^hambers had developed for micro- 

 mani|)ulation. Portions of muscle fil)ers, 3-5 mm. long, 

 from the sartorius of the /Vo// were ])laced in a hanging 



