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JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



here for more than three hundred years than when it was introduced — 

 two or three degrees of frost are sufficient to destroy its leaves — and 

 this in spite of several generations having been raised from seed ; runner 

 and French beans and vegetable marrows are the same now in this 

 respect as when they were introduced; indeed, in the case of beans 

 definite selection of those which withstood frost better than others of 

 the same variety and the continuance of the race by seed saved from 

 these survivors has not yielded a race one whit hardier than the species 

 was when it first came to this country. Now and then examples are 

 given of plants surviving under circumstances where others of the same 

 species are killed by frost;''' but these instances are few, and it would 

 seem that the permanent change of the character of a plant so that it 

 will withstand greater degrees of cold than when it was first intro- 

 duced is at present beyond our powers to induce. We have no authentic 

 instance of the acclimatization of a plant which proved tender when 

 first grown. It would seem that the plant's relation to temperature 

 depends in the main upon the nature of its protoplasm. 



There is little doubt that the extent of the damage done was 

 greater than it otherwise would have been in some places because of the 

 continuous mild weather immediately preceding the first sharp spell in 

 December. The reports state that several plants kept on growing when, 

 under cooler conditions, growth would normally have ceased. It cannot, 

 however, be said that in the dry soil at Wisley this was the case; on 

 the whole there the summer's growth ripened fairly well and yet many 

 plants suffered. 



It seems certain, however, that plants which from their position in 

 the garden are encouraged to continue long in growth, or to make 

 growths slow to ripen, will be the ones most likely to fall victims to 

 extremes of cold. In other words, parts of plants in which the proto- 

 plasm is in an active state are more likely to succumb to low tempera- 

 tures than those in which the protoplasm has gone slowly to rest. 

 Protoplasmic activity is always associated with abundant supplies of 

 water, and so soft and sappy or ill-ripened wood is the first to suffer. 

 The behaviour of winter vegetables during the period is instructive. In 

 many gardens they were completely destroyed, but where it was 

 possible for comparisons to be made between those which had been 

 encouraged to continue growth late in the season by the application of 

 nitrogenous manures, and others that had gone more or less to rest 

 after their first growth-period was finished, it was invariably found that 

 the latter suffered less and sometimes escaped altogether (see, e.g., 

 p. 77). It is probably on account of a factor such as this that some of 

 the rather curious differences in behaviour reported concerning a few of 

 the plants mentioned above are due. Some of them, because of greater 

 shelter or a more abundant water supply, kept on growing longer in the 

 autumn than their neighbours and suffered greater damage. 



* " I know of no well-authenticated instance of plants which have acquired 

 hardiness after long cultivation in a colder country. I have cases in my own 

 garden this winter, amongst which I may mention Eucalyptus Gunnii, of which 

 seedlings raised from Scotch-grown trees have proved more tender than seed- 

 lings raised from trees in the South of England, and I think that this is 

 due to hereditary constitutional debility." — H. J. Elwes in litt. (1909). 



