FISHERIES, GAME AND FORESTS. 433 



willing to go without danger of injuring the next season's crop, as by reason of their 

 depth and perviousness is the case with most California soils. 



In illustration of these views Professor Hilgard submits two views of typical root 

 systems at the East and in California. In the first the roots are shown branching out 

 laterally, as is the case of all tree growth, especially in the State of New York, and 

 only penetrating a very few feet. In the illustration of tree root growth in California, 

 he shows a photograph of a prune tree grafted on a peach root where the main roots 

 extend down nearly vertically into the ground to a depth of from seven to ten feet. 



It seems clear, therefore, that, as a result of these California studies, we must amend 

 our view that forest trees will not grow in regions with deficient rainfall. Obviously 

 the controlling condition is penetrability of soil rather than quantity of precipitation. 

 These facts also lead to the tentative conclusion that forests require for growth 

 considerably less water than agricultural crops, although it may be borne in mind that 

 vigorous growth in forests, the same as in agriculture, is stimulated by an 

 abundant water supply. 

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