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point (botweoii V and 1> in the titriiro). At'tor death, more 

 water freezes mit wlieii the temperature is hnvered ( rei!:ioii 

 D in tlie figure). Tf death, in thesi' ex])erinients, took 

 ])hiee while the material was I'l-ozeii ( and not on thawinir), 

 it did not correspond to the removal of the most tightly 

 bound water, since some was still unfrozen after death. 



This observation led Lnifet (1U-11>) to distinguish be- 

 tween fitdl and hound (unfreezable) water. There woidd 

 be 5 kinds of water in protophism : 1. Excess water which 

 can be removed without atlt'ecting the activity of ])roto- 

 plasm; for examiile, without decreasing the res])iratory 

 rate. '2. Mifuholic water which iiithiences the ratt' of liv- 

 ing processes but can be withdrawn without inducing 

 death. 3. Vital water, tlie separation of which is lethal. 

 4. Boinunit frcczabic water which, in some organisms, 

 stays unfrozen during death by congelation but can ])e 

 frozen after death. 5. U)ifrrezahlc water which never 

 freezes at any temperature. The author accounts for the 

 speeilic differences in cold resistance by assuming that, in 

 some types of protoplasm, the vital water is the most 

 tightly bound, unfreezable water, \\ hiU', in others, it is the 

 freer, freezable water. 



Becquerel (1939) claims that cells killed by freezing do 

 not show any evidence of having been dehydrated by 

 plasmolysis. He ex])osed e])idermal stri])s of onion or of 

 the petals of red hyacinth to temjieratures extending 

 from -150" to -25"^ and examined individual cells under 

 the inicrosco])e before, during and after freezing and 

 thawing. He observed that neither the cytojilasni, nor the 

 vacuole nor the nucleus undergoes any change which 

 might be interpreted as resulting from ])lasmolysis. He 

 concludes that ''almost all the physiologists so far have 

 made the mistake" of considering as plasmolysed a coag- 

 ulated c^'toplasm slightly separated from the cell wall. 

 It seems that the condition reported by Becquerel is due 

 to the fact that he used a rapid method of freezing which 

 did not allow plasmolysis, which is usually a slow proc- 

 ess, to take place. 



