274 



THE GA RDENER'S MONTHL Y 



[September., 



final effect upon the plant, as upon the freezing. 

 Somewhat tender plants supposed to be frozen, 

 and certainly coated with ice, may frequently 

 be saved by placing them in cool, shaded posi- 

 tions, or in cold water while thawing. So ap- 

 ples in tight barrels, shaded from the sun, or 

 buried in the ground, may be subjected to al- 

 most any degree of frost, and if afterward 

 slowly thawed in these situations, are slightly or 

 not at all injured, while if thawed in the sun 

 they quickly decompose. 



What is ^the explanation of these and similar 

 phenomena with which every one is familiar? 

 No doubt some of the changes and their causes 

 are not yet well understood, but much certainly 

 is known, the main portions of which can be 

 given in a few words. 



If fermented cider is exposed to a tempera- 

 ture below that at which water solidifies, some 

 persons have found out that the part which be- 

 comes ice is not cider at all, but upon removal 

 and thawing is very near pure water, while the 

 unfrozen portion is cider with emphasis. On 

 one occasion a very estimable young man, well 

 known to the writer, at an evening party learned 

 this latter fact in such a practical manner that 

 he has never forgotten that apple cider kept in 

 a barn in Winter and drawn by boring through 

 ice is intoxicating. Those who hang wet clothes 

 upon Hues to dry in Winter speak of them as 

 freezing dry. The fact is the water, closely 

 held in the fabrics by capillary attraction, is ex- 

 tracted, brought to the surface, by the action of 

 the frost, and is carried oft" by the air currents. 

 The withdrawal of the water from the cloth is 

 precisely similiar to its separation from solu- 

 tions, as cider, sweetened water, salt water, etc. 

 The process is somewhat as follows: Upon 

 the withdrawal of heat, the molecules com- 

 posing water, previously moving freely with 

 little or no friction upon each other, thus 

 forming a true liquid, approach and cohere, 

 forming a solid. But the attraction which thus 

 binds together the molecules of water does not 

 exist between those of water and the commin- 

 gled molecules of other substances, hence these 

 latter do not become attached ; they remain float- 

 ing in the still liquid portion. Ice having 

 formed upon the surface, and consequently 

 withdrawn particles of water from this immedi- 

 ate portion, equalization takes place in the re- 

 mainder through the law of diffusion. Thus 

 other molecules of water are brought in contact 

 with those solidified and the ice becomes thicker 



from additions upon the liquid side. Diffusion 

 and equalization again taking place, the process 

 is continually repeated, the pure water being 

 extracted and the solution gradually condensed. 

 The more watery the solution the more readily 

 the operations are effected, that condensed and 

 thick yielding slowly or not at all to the forces 

 tending towards the result. 



• Now, all this is true in the case of the semi- 

 fluid substances of plants. Green leaves and 

 young stems may be observed coated with ice 

 from the water extracted from the tissues, and 

 yet close observation may show that the tissues 

 themselves are still flexible, not frozen. This 

 is beautifully shown in the little plant, often 

 used for bedding purposes, known on account of 

 the peculiar shape of the flower as the cigar- 

 plant. If subjected to below 32^ Fahrenheit in 

 a damp still atmosphere, the roots being in 

 moist soil not too cold, a layer of ice will be 

 formed around the young stems of such thick- 

 ness that it may be taken off as stout scales, 

 separating readily sometimes from the still 

 flexible plant. Upon close examination this ice 

 is found to be composed of elongated crystals, 

 radiating from the stem. Having received ac- 

 cessions from the plant end, the older portions 

 of these crystals have been continually pushed 

 outward. This loss of water leaves the half- 

 fluid substances of the plant thicker or more 

 condensed, unless, as may happen, the roots 

 have kept up the supply. Often the ice forms 

 within the tissues instead of outside, but it may 

 then be found in localized places, the cells, per- 

 haps, having been forced asunder by its expan- 

 sion. In this case the collection of the ice 

 crystals is the same as indicated above. The 

 simple rupturing of cells, or their forcible sepa- 

 ration, though not a good thing for the plant, 

 need not cause death. By the extraction of heat 

 and water the bark and outer layers of wood 

 may shrink with such force as to cause cracks 

 more or less deep in trunks and large limbs, but 

 the tree may survive without apparent injury 

 and the wounds rapidly heal. 



If after the water of the cell-sap is thus 

 partially congealed, — either without or within the 

 tissues, — thawing take place very gradually, it 

 may be again absorbed and the normal condi- 

 tion restored. Anything which arrests evapo- 

 ration, as sprinkling or plunging in water, has the 

 same effect. The condensed, partially dried 

 protoplasm and cell-sap receive the necessary 

 amount of water to permit them to perform 



