CH. IX.] DEATH AND DECOMPOSITION. 323 



thus deficient of carbon and hydrogen, the chief 

 constituents of their colouiing matter, they become 

 unnaturally pale. 



It must not be omitted to be observed, that all 

 plants have a great power to resist the reduction, as 

 well as the elevation, of their internal temperatm-e, 

 however low may be that of the air which suiTounds 

 them. In the polar regions, and even in those of 

 less northern latitudes, they have to endure a tem- 

 perature ten and more degrees below the freezing 

 point of water — yet their sap is never known to 

 freeze. If water does congeal in the texture of a plant 

 it rifts it, but this never occurs unless extraneous 

 moisture has penetrated through some wound or 

 decayed part. I have seen trees so torn, but never with- 

 out finding a mass of ice within the trunk or branch 

 traceable to some outward fissure. This is entirely 

 in accordance with the the experiments of Mr. John 

 Hunter; and other experiments which I have tried, 

 confirm me in acceding to the conclusion to which 

 that distinguished anatomist, as well as Sprengel, 

 Schluber, and others have arrived, that the sap of 

 healthy plants never congeals, however low the tem- 

 perature to which they are exposed. Even in a 

 temperature fifteen degrees below that at which the 

 sap, if taken from the tree, would freeze, yet, in the 

 living plant, it remains uncongealed. This has been 

 tried upon the vine, walnut, elm, and red pine. 



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