18 The Principles of Fruit-growing. 



350 grams of moisture." These calculations, there- 

 fore, may explain some of the injuries which follow 

 very dry winters. 



Since evaporation takes place through the bark 

 of winter twigs, it is reasonable to suppose that the 

 tenderness of some trees in dry winter climates (as 

 in our plains regions) may be due to such an ana- 

 tomical structure of the bark as does not resist evap- 

 oration, and that, on the other hand, hardiness may 

 sometimes be a matter of thickness or denseness of 

 bark. Studies in this direction have been made at 

 Cornell, and they indicate that this supposition may 

 be well founded in certain cases, but the investi- 

 gations are not yet sufficiently extended to allow 

 of any definite statements. 



The soil determinant. There are special adaptations 

 of fruits to soils. Pomologists are well aware of 

 this fact as a general truth, but very little close 

 attention has been given, in this country, to the 

 minor applications of it. To be explicit, it is well 

 understood that pears flourish best on clay soils and 

 peaches best on sandy soils, but there are, no doubt, 

 distinct preferences amongst the varieties of pears 

 and peaches themselves. It is possible, in fact, that 

 each distinct family or type of varieties of any 

 species has preferences of land and location, and it 

 will be the business of coming generations to de- 

 termine what these peculiarities are. With the in- 

 creasing refinements and competitions of the future, 

 the special and local problems must receive more and 

 more attention. If these positions are well taken, it 



