44 WINTER FIELD MEETING. 



If the living cells of plants froze, as we accept the term, 

 they would burst in the manner a bottle of water bursts 

 when frozen ; but the process of freezing in plants is 

 conducted upon a different plan. 



The water before it freezes is discharged from the cells, 

 and the crystals of ice are formed not in the cells, but out- 

 side of them, often however, tearing the tissues of the 

 plant. This happens to nearly every annual or herbaceous 

 plant. To-day, the great Castor-oil Beans and Cannas 

 of our gardens are a magnificent mass of living foliage. 

 A night frost comes, and to-morrow their leaves hang 

 limp and lifeless. This is because the cells of which 

 they are composed were all, or nearly all, living cells 

 and gorged with water. 



In freezing, the cells of the tissues of the plants were 

 suddenly deprived of the water they contained, and the 

 cells were killed either by the continued cold, or in case 

 of a thaw, by being unable to reabsorb, with sufficient 

 rapidity, the water of which they were deprived by the 

 cold. 



How is it, then, that the living cells of the trees are 

 enabled to withstand cold very much more severe than 

 that which kills the annuals of our gardens and fields? 



If we cut across the trunk of any of our forest trees, 

 we notice numerous rings, which, if counted, tell accu- 

 rately the age of the tree. Favorable and unfavorable 

 seasons may be detected by the width of these rings. In 

 tropical countries, the rings of growth are less distinct, 

 and in some trees quite imperceptible. This is because, 

 in our climate, the tree, as winter approaches, prepares 

 itself by filling the living cells with mucilaginous matter, 

 and by withdrawing from them the water, so that these 

 cells do not freeze, as we use the word. 



In making this preparation for winter, the wood cells 



