Addresses — Conditions of Hardiness. 179 



ard of hardiness, as our climate and soil differs from that east of the 

 Great Lakes in the same latitude. It is these new conditions of 

 climate and soil that drive us to the most rigid test of all new sorts 

 that come up for trial. 



The conditions affecting the hardiness of a tree may be arranged 

 under four distinct general divisions, namely: 



1. Organic. Structural, including variety, etc. 



2. Geological soil formations. 



3. Climatic. Temperature and saturation or moisture. 



4. Location and culture, including pruning and general care. 



That woody growths differ in their organic structure, is a mat- 

 ter of common observation; but to show the relation between such 

 differences and capacity for enduring climatic changes, has been 

 too generally overlooked by scientific observers. Two years ago I 

 spoke of this subject before this society in these words: " Woody 

 structure is made up of vegetable fibre, which holds the sap in 

 various stages of development toward organized matter. This veg- 

 etable fibre contracts with cold, while the sap expands with any 

 degree of cold sufficient to congeal it (pure water expands below 

 39 deg. F.). This contraction and expansion is a severe strain 

 upon the cellular structure of a tree, and a rupture of its cells 

 produces some form of disease. Now, the capacity of a tree or 

 plant for enduring repeated extremes of temperature, or in com- 

 mon terms, hardiness, is measured by its toughness or strength of 

 fibre, and the size of its sap vessels. Thus the section of Rhode 

 Island Greening shows a much larger proportion of porous wood 

 than the native crab, and equal sized sections of each variety, dry, 

 will show a difference of twenty per cent, in weight in favor of the 

 crab wood. The same will hold good with all wood growth of a 

 given species and climate. There will be a corresponding difference 

 in their capacity to resist the changes of temperature as indicated 

 in this test, allowing something for the operation of the vital force 

 in all cases." 



The question of " vital force " is one on which science is at 

 variance. Some claim that there is no inherent vitality in living 

 objects, but that organized matter is built up and lives by a gen- 

 eral law of growth or matter in motion. Whatever may be the 

 true theory of life or action in organized matter, we know that 

 while individuals differ largely in their native vigor and endurance. 



