icn 



oulc'clic I'rtM'/iiii;', should Imi'dl}' l»c noticed ;nid could iiol l)o 

 as lar^e as was (»l)sci\-cd. lie cxpressctl his siir])riso at 

 Mez' c'oiiloulioii thai the ciiU'ctic was always above -fi°, 

 wliiMi it is known that solutions of several snl)stances found 

 ill the cells have mncli lowci- eutectic points. He em- 

 phasized the faet that, in the numei'ous curves tliat lie 

 estal)lished with tissues or with extracted juices, he never 

 observed any indication of a eutectic freezing. He also 

 pointed out that, with the high cooling velocities used by 

 Voigtljindei', any retardation in the slant of the curve 

 would be so attenuated that even the freezing points would 

 be obscured. He finally suggested that the two retarda- 

 tions observed by that author were due, respectively, to 

 a freezing of the cell sap extruded around the thermocouple 

 by the insertion of the latter, and to the freezing of the 

 tissue. This interpretation was confirmed by the fact, 

 meniioned by Voigtliinder himself, that extracted juice 

 gave but one retardation. 



Luyet and Gehenio (1937) showed that a living tissue 

 which gives a curve with two long horizontal plateaus (Fig. 

 23, A), at a low cooling rate of 2.5 degrees per minute, 



5 10 15 20 MIN 



Fig. 2o. Effect of i-ooliiig vulucity on freezing curves. (From Ijuvt't and 

 Gehenio, 1937.) Cooling velocity at 0°: in curve A, 2.5° per minute; in 

 curve B, 5.2" per minute. 



gives a curve in which the plateaus almost vanish at a cool- 

 ing velocity of about 5 degrees per minute (Fig. 23, B), 

 and would be replaced by two slight retardations at the 



