302 Observations upon the effects of Frost, 



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 phy- 

 sical effects of cold upon vegetable matter already dead. For the 

 purpose of judging how far this conjecture is well founded, I 

 have carefully examined the post mortem appearances of several 

 plants killed by exposure to a temperature artificially reduced only 

 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 important. 



I could not find the vesicles of cellular tissue separable from 

 each other, even in the most succulent species submitted to experi- 

 ment, and I conclude that this circumstance, to which Professor 

 Morren attaches importance, and to which M. Payen ascribes the 

 difficulty of extracting starch from frozen potatoes, is not so much 

 connected with the destruction 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 had been extended with but little power 

 of recovering itself again, and several large irregular lacerated cavi- 

 ties were observed. The same appearances were remarked in 

 Euphorbia Tirucalli, but the laceration of the tissue was much less 

 extensive. In Hibiscus Rosa Sinensis the cells of the cortical inte- 

 gument (mesophlceum) were very much torn, and in Hibiscus mili- 

 taris not only the cells of the bark, but especially those of the pith, 

 were so completely broken up that it was difficult to obtain a thin 

 slice of those parts for examination. In no case, however, have I 

 found any kind of tissue ruptured except the soft cellular dodeca- 

 hedral or prismatical. It would also seem, that M. Payen recog- 

 nizes the laceration of tissue by frost, for he ascribes the acridity of 

 frozen potatoes to an extravasation of the acrid matter which exists 



