Addresses — Conditions of Hardiness. 183 



frost on vegetable fibre and watery fluids of the tree, have an 

 important office in expanding the cells and softening the fibre, but 

 if too abrupt in either the freezing or the thawing process, the 

 results will be disastrous. So we want the changes of temperature 

 to be gradual and in their regular order and season. 



See American Journal of Science and Art, March, 1840, for 

 paper by Dr. Lindley on " Frost." 



Climatic influences are so much modified by altitude, aspect and 

 drainage, that these fill a large place in the conditions of success. 

 Comparative elevation secures exemption from extreme heat and 

 cold to a remarkable degree, and at times when the tree is in most 

 danger. Thus an elevation of thirty feet above the surrounding 

 level, and a northern aspect, saved our nurseries April 15th, 1875, 

 when on a lower level and southern aspect not eighty rods away, 

 every tree was as good as ruined. In the latter case, the trees had 

 passed into the sappy state of spring growth, and when the mer- 

 cury fell to 15 deg., as it did the night of the 15th, it carried death 

 to the tree. In the former case, the cooler aspect and elevation 

 retarded growth until the danger was passed. Comparative eleva- 

 tion of thirty feet may give 10 deg. less of heat in the warm days 

 of February and March, with 5 deg. less of cold the following 

 night, against that on the ordinary level. The same situation may 

 have a temperature of 35 deg. on a cool night, blooming time, 

 when the other has that of 28 to 30 deg., which will generally kill 

 the young fruit. This illustration, so familiar to all practical fruit- 

 growers, shows the importance of location. 



I may say here also that under-drainage is another factor of suc- 

 cess, for it not only promotes early maturity and ripeness of wood, 

 but often secures 2 to 5 deg. of heat in frosty nights when the crop 

 of fruit is in danger from frost. 



The foregoing are natural conditions, but we have in our fourth 

 general division another series of conditions, artificial, such as 

 mode of propagation, culture, fruiting and pruning. Some 

 claim that the use of a hardy stock will make a hardy tree, and 

 maintain that even a half-hardy variety may be so grown and be 

 successful. We have no warrant or analogy in nature for this 

 claim. It is a delusive theory. If the stock could give character 

 to the cion, such would be manifest in more ways than one. The 

 stock is but the vehicle by which raw material in solution is con- 



