DESTRUCTION OF PLANTS BY FROST. 



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 ascertain the cause of these phenomena, and the following is what observation 

 has shown me. I studied for this purpose, more particularly the tissue of t-he apple. 

 Each cell is filled with a small icicle, which has in its middle a bubble of air. We know 

 that when water freezes, the crystals so arrange themselves, that the air separated from 

 their mass b}^ the solidification of the liquid is intercalated between their j)laiies. This 

 air also places itself in a mass of congealed water in a regular manner, the nature of which 

 depends entirely upon that assumed by the crystals, as may be seen by freezing water in 

 a cylindrical vessel, when the air-bubbles always assume the form of a very long cone, 

 terminated by a spherical cap. The augmentation of the volume of water is in a great 

 measure owing to this interposition of masses of air. All these effects take place in each 

 cell of a frozen apple, which thus increases in size because each cell of its tissue becomes 

 individuall}'- larger. When thawed, the cell recovers itself by the elasticity of its vegeta- 

 ble membrane, and frozen fruit becomes, as we know, very much shriveled. Each cell, 

 therefore, acts like a bottle of frozen water, only there is no bursting, because the mem- 

 brane is extensible.' 



" But when plants easily killed by cold, are exposed to so low a temperature as that 

 just described, it is to be feared that phenomena actually connected with the destruction 

 of vegetable life, may be intermixed with others, which merely indicate the physical ef- 

 fects of cold upon vegetable matter already dead. For the purpose of judging how far this 

 conjecture is well founded, I have carefull}^ examined the post mortum appearances of se- 

 veral plants killed by exposure to a temperature artificially reduced onl}' to from 28" to 

 30" Fahrenheit. These observations, while they have confirmed the general accuracy of 

 Professor Morren's statements, have led to other conclusions which also appear impor- 

 tant. 



" I could not find the vesicles of cellular tissues separable from each other, even in the 

 most succulent species submitted to experiment, and I conclde that this circumstance, to 

 which Professor Rlorren attaches importance, and to which M. Payen ascribes the difficul- 

 ty of extracting starch from frozen potatoes, is not so much connected with the destruc- 

 tion of vegetable life, as a result produced upon the tissue by a great intensity of cold. I 

 did, however, find it lacerated in several cases, as if by the distension of the fluid it had 

 contained. In a Stapelia the whole of the cellular tissue was soft, and deformed, as if it liad 

 been extended, with but little power of recovering itself again, and several large irregular 

 lacerated cavities were observed. The same appearances were remarked in Euphorbia Ti- 

 rucalli, but the laceration of the tissue was much less extensive. In Hibiscus Fiosa Sinen- 

 sis the cells of the cortical integument, (niesophloeuin,) were very much torn, and in Hi- 

 biscus militaris, not only the cells of the bark, but especiall}' those of the pith, were so 

 completely broken up, that it was difficult to obtain a thin slice of those parts for exami- 

 nation. In no case, however, have I foimd any kind of tissue ruptured, except the soft 

 cellular dodecahedral or prismatical. It would also seem that M. Payen recognizes the 

 laceration of tissue b}' frost, fjr he ascribes the acridit}' of frozen potatoes to an extrava- 

 sation of the acrid matter which exists in the epiphloeum of such tubers, and which, in a 

 natural state, is locked up in the cells of which that part consists. Independently of these 

 observations, it is not to be doubted that frost does split the tissue of plants. I saw the 

 youngest shoots of Erica mediterranea, cinerea, and others, shivered into thousands of 

 pieces in the Horticultural Society's Garden, on the morning of the 20th of January. The 

 branches of the Melaleucas were rent to their points at Carclew. Several cases, amono' 



