74 



EFFECTS OF FROST ON TREES. 



the top of the old one, so that a root origi- 

 nally planted four inches deep, gradually 

 approaches the surface till it is almost bare. 

 Owing to this, it is often destroyed by the 

 winter. To make sure against this, the 

 better way is to protect it by throwing a 

 couple of shovelfuls of soil over the root in 

 the autumn, and removing in the spring. 



I obtained all the foregoing species from 

 Mr. Hogg, of New-York, who pays especial 

 attention to the culture of this class of 

 plants.* 



Yours, respectfully. 



An Amateur. 



New-York, July 9, 1&17. 



* [Mr. Hogg's collection of herbaceous plants is one of the 

 largest and best in the country. — Ed.] 



PHYSIOLOGICAL EFFECTS OF SEVERE FROST ON TREES. 



Translated for this Journal, by Dr. A. GERALD HULL, Newburgh, N. Y. 



Since the establishment of the Royal Soci- 

 ety of Horticulture, at Paris, there have 

 been received and published many facts ex- 

 hibiting the disastrous effects of intense 

 cold on vegetation ; but these have not been 

 explained by the Society, or, rather, have 

 been attributed, according to the generally 

 received opinion, to an unusual dilatation 

 of the tissues dependent on the congelation 

 of the liquids contained in these same tis- 

 sues, on the principle that a piece of ice oc- 

 cupies a greater space than the liquid which 

 forms it. This view of the subject compels 

 us to admit that there are some tissues 

 much more dilatable than others ; other- 

 wise we could not explain why the common 

 House-Leek, a very watery plant that grows 

 on our thatched cottages, resists the most 

 vigorous winters, while other plants, of a 

 less succulent tissue, perish. We believe, 

 and with much reason, that the physical 

 constitution of every vegetable is such that 

 it can sustain a given amount of cold, but 

 that there is no mode of discovering, a pri- 

 ori, this property in the tissue. Experience 

 alone can teach us. 



M. Charles Morren, Professor of Bota- 

 ny in the University of Liege, having made 

 observations on the effects of the winter of 

 1837-8, and relying on the one base, that 



sap is not pure water, and on the other, that 

 water, which is not pure, does not freeze as 

 readily as that which is pure, has reached 

 conclusions which are calculated to modify 

 the manner of estimating the cause of de- 

 struction to plants during severe winters. 



M. Morren, having presented his con- 

 clusions, under the form of ten aphorisms, I 

 transcribe them here, as they were publish- 

 ed in the Echo du Monde Savant, on the 

 27th of March, 1839. 



1. No organ of plants is rent by the ac- 

 tion of cold, except in a few rare cases, 

 where the cavities of the cellular tissue 

 yield to the effect of the dilatation of the 

 liquid. 



2. The organs contained in the cells or 

 vessels,* do not undergo any change ; the 

 fecula, perhaps, excepted under some cir- 

 cumstances, when changed into sugar, 

 doubtless through the agency of an acid, 

 derived from the decomposition of the or- 

 ganic parts. 



3. The intercellular passages (les bifori- 

 nes,) do not cease, after freezing, to eject 

 their raphides, (minute crystals found in. 

 certain living plants — Trans.) and thus it 

 is probable that this movement is not due 

 to a vital contractility. 



* Come rendochrome, !e nucleus, le fibre, la fecula, les 

 raphides, et les crisieaux. 



