Moisture and Fruit-growing. 9 
degrees of latitude (reaching northwards to about 
27°). Beyond all these bounds there are special 
localities in which fruits of the adjacent zone may 
thrive for a series of years, and the fruits of con- 
tiguous zones overpass. The strawberry is probably 
the most tractable of all our fruits as respects 
climates, because its stature and habit allow it to be 
protected from extreme cold and its short period 
of growth allows it to thrive in the cool season 
of the warmest sub-tropical regions. 
The annual temperature of a region is chiefly 
determined by three factors,—the latitude, the 
altitude, and the proximity or remoteness of large 
bodies of water. 
The moisture determinant.— The second chief fac- 
tor of climate in determining the fruit-zones is rela- 
tive humidity. Whilst the isotherms—or lines of 
equal temperatures—run easterly and westerly, the 
isohyetals—or lines of equal rainfall—have no in- 
trinsic direction. They are determined by physio- 
graphical characters. In the United States, there are 
three general fruit-zones which are marked by pecu- 
liarities of rainfall. These are the Atlantic zone, 
a moist area which is bounded westward approxi- 
mately by the Mississippi River; the plain zone, 
extending westward to the mountains; and_ the 
Pacific slope zone. The two latter are relatively 
dry.* The interior or plains region is particularly 
*We should, perhaps, make a fourth division, to comprise the arid or 
Sonoran zone of New Mexico and Arizona, but this area is yet too little 
known in a pomological way to demand specific treatment here. 
