66 PLANT LIFE OX THE FARM. 



as the Blood Bed is very hardy, owing its immunity possi- 

 bly to it's habit of keeping its leaves close to the ground 

 during the winter and spring, and, therefore, less exposed 

 to sudden changes of temperature. In any case, its 

 leaves are more likely to be protected by a coating of 

 snow. The selection, therefore, of the kind of wheat 

 best adapted for Scotland, for the eastern or for the 

 western counties of England respectively, is a matter of 

 great consequence. A variety which succeeds in a warm 

 moist climate would be quite unsuitable for a drier one, 

 even if the temperature sometimes rose higher. 



In moist air it has lately been shown by M. Vesque 

 that the leaves are both thinner and longer than when 

 grown in dry air, that the vascular bundles of the stem 

 are also thinner, and less perfectly developed than in 

 dry air. Thus, the effects of a saturated atmosphere on 

 the growth of leaves seem to be very similar to those 

 mentioned by Rauwenhof as characteristic of plants 

 grown in obscurity. When fully exposed to the light, 

 in a dry, hot, stagnant atmosphere, where transpiration 

 from the surface of leaves is ample, the leaves become 

 thicker, their anatomical structure is altered, and they 

 show a tendency to become more hairy. 



It would not be worth while for the agriculturist to 

 try and make his plants adapt themselves to different 

 conditions as the experimentalists and physiologists do, 

 but the indications and facts brought forward by the lat- 

 ter may very profitably influence the farmer's selection 

 of the particular varieties best suited, by their conforma- 

 tion or structure, to meet the vicissitudes of particular 

 localities. 



The Influence of Contact on Leaves. This may be 



dismissed with a few words only, as it is not, so far as at 

 present known, of much practical importance to agricul- 

 turists. In addition to the movements immediately con- 



