Effects of Frost on Platits. 23 



rophyll, the nucleus of cells, elementary fibre, amylaceous mat- 

 ter, raphides, nor the various crystals contained in vegetable tis- 

 sue, undergo any alteration, unless perhaps in the case of amy- 

 laceous matter, which in some cases is converted into sugar, no 

 doubt in consequence of the action of some acid formed by the 

 decomposition of the organic parts. 3. That the action of frost 

 operates separately upon each individual elementary organ, so 

 that a frozen plant contains as many icicles as there are cavities 

 containing fluid ; the dilatation thus produced, not being sufficient 

 to burst the sides of the cavities. 4 That such dilatation is prin- 

 cipally owing to the separation of the air contained in the water. 

 5. That this disengagement of air by [from?] water, during the act 

 of congelation, is the most injurious of all the phenomena attendant 

 upon freezing ; introducing gaseous matter into organs not inten- 

 ded to elaborate it, and bringing about the first stage in a decom- 

 position of the sap and the matters it precipitates ; so that with a 

 thaw, commences a new chemical action destructive of vegeta- 

 ble life. 6. That the expansion of the cells and aquiferous or- 

 gans, drives a great quantity of water into the air-cells and air- 

 vessels, so that the apparatus intended to convey liquid only, con- 

 tains water and air, while that which is naturally a vehicle for air 

 conveys water. Such an inversion of functions must necessarily 

 be destructive to vegetable life ; even if death were not produced 

 in frozen plants by the decomposition of their juices, the loss of 

 their excitability, and the chemical disturbance of all their con- 

 tents. 



" Professor Morren's observations were made upon various plants 

 frozen in the spring of the present year, having been exposed to a 

 temperature of — 4^^ to +9° Fahrenheit. One of his statements 

 I give in his own words. ' In the parenchyma of many plants, 

 and especially in that of succulent fruits, it is easy to ascertain 

 what modifications are caused by frost in the internal organs of 

 plants. If a frozen apple is opened, it is obvious that the ice is 

 not a continuous mass, but that it is a collection of a multitude of 

 little microscopical icicles. Under the microscope the fact be- 

 comes evident. We know how excessively hard some fruits be- 

 come when frozen by this mosaic of icicles, especially pears. If 

 we thaw them, it is seen that on the instant a multitude of air- 

 bubbles are extricated from the juice of the fruit, and that this 

 juice has then acquired new chemical qualities. I wished to as- 



