392 THE MAGAZINE OF HOKTICULTURE. 



tion of the tissues did not produce injury, as generally supposed, was suffi- 

 ciently shown by the well-known fact that the same degree of cold acted 

 very differently on different plants placed in equal circumstances. 



Mr. Moore did not consider the reasons given by Dr. Steele for objecting 

 to the generally received opinion on this subject to have been happily con- 

 ceived, inasmuch as animals which are natives of warm countries are more 

 subject to be destroyed by cold than those which are natives of colder re- 

 gions. Nature provides both plants and animals Avith tissues capable of 

 resisting the rigors of the climates they were destined to live in. He had, 

 therefore, no doubt but that the action was of a mechanical nature, and 

 caused by the rupturing of the walls of the tender cells, which he believed 

 was ih^ opinion of the most distinguished botanists both in this country and 

 on the continent of Europe. It was a very common occurrence to see the 

 bark of plants that had been injured by frost part from the wood. Now, 

 every vegetable physiologist knew that a layer of soft mucilaginous matter 

 existed between the wood and bark of all exogenous trees, called cambium, 

 out of which young cells were being formed, which had very long and 

 slender walls at first, and it was known to be the congelation of that sub- 

 stance, and rupture of the tender cells, which causes bark to part from the 

 wood. The chairman also had frequently remarked, when pelargoniums 

 are destroyed by frost, that the wood separates from the bark, and he be- 

 lieved the effect of frost on plants to be a mechanical action which ruptured 

 their tissues, and not a sudden shock. 



This is so interesting a question that we just venture to occupy a brief 

 space with a remark or two which we hope may help to throw some light 

 upon it. 



That the action of frost is purely mechanical is an old doctrine which has 

 met with general assent. It has been held that when a plant is frozen the 

 fluids contained in its cells expand, and rupture the tissue, thus producing 

 disorganization. That this is to some extent true is, we believe, indisputa- 

 ble ; some observers have reported that they have seen proofs of such an 

 action. It has been therefore suggested that the fluids contained in differ- 

 ent species of plants may themselves act differently in the presence of cold ; 

 just as oil' of turpentine requires a temperature of 14° to freeze, while oil of 

 bergamot freezes at 23°, and olive oil at 36°. But although this may be 

 true to a limited extent, yet it by no means explains the phenomena in 

 question. The plant x, for instance, perishes from frost, while another, 

 identical with it in nature, lives with impunity within two yards of it, both 

 having been exposed to the same temperature. In this case the fluids of 

 the two will be chemically the same, and yet the results are opposite. 

 Again, the long-leaved pine (P. longifolia) is quite tender, while the Gerard 

 pine, exceedingly like it, is hardy ; in this case there is no ground for sup- 

 posing that the fluids contained in these species are different. In fact, ex- 

 cept that all plants suffer from cold in proportion to the quantity of water 

 they contain, we have no kind of evidence to show that the quality of their 

 fluids has any material influence upon their power of resisting cold ; for it 

 is by no means true, as some too hastily assert, that resinous trees, like 



