New YorK AGRICULTURAL EXPERIMENT STATION. 351 
York, valleys, large or small, protected from cold winds, open to 
sunshine, free from fogs, or comparatively free from frosts, which 
have advantages in these respects over other areas better situated 
as to latitude. In such favored localities adverse influences of 
latitude are offset and the list of desirable fruits is increased. 
Temperature—— The chief factor in determining the distribution 
of fruits is temperature. Each fruit requires a certain amount of 
warmth for its development and can endure but a certain degree of 
cold. Investigations conducted by the Division of Biological Survey 
of the United States Department of Agriculture enabled them to lay 
down the following law * regarding temperature as a means of con- 
trolling the distribution of plants and animals. “ The northward 
distribution of terrestrial animals and plants is governed by the sum 
of the positive temperatures for the entire season of growth and re- 
production, and the southward distribution 1s governed by the mean 
temperature of a brief period during the hottest part of the year.” 
In fruit-growing it is found that the distribution of fruits and their 
varieties conforms to this law only in a broad and general way and 
yet sufficiently closely that we may make it a means, as accurate or 
more so than any other rule that has been laid down, of studying 
the relations of climate to the life events of plants and to the distri- 
bution of varieties. 
The fruit-grower is chiefly concerned with the annual tempera- 
ture and this is determined by latitude, altitude and proximity to 
large bodies of water. Variation in the surface of the country — 
hills and valleys —are often modifying agents of temperature and 
especially of spring and fall frosts. The warmth-retaining prop- 
erties of the soil must often be taken into account. Beyond all 
question, the last named factor does not receive sufficient consid- 
eration and we shall often find that the adaptations of some varieties 
of fruits, especially of grapes and peaches and of some apples, 
which prefer warm soils, as sands and loams, depend largely upon 
the heat in the soil. 
Water—All plants are very sensitive about their supply of water 
and with a species which has been cultivated as long as the apple 
*U. S. Dept. Agr., Biol. Surv. Bul. No. 10, p. 54. 
