|THE PHYSIOLOGICAL ASPECTS OF CALIFORNIA FOR THE BOTANIST|
IT is almost absurd to speak under one title of a region which forms the Pacific coast of the United States for a distance equal to that from Key West to New York, which extends from sea-level to almost three times the height of Mt. Washington and from the Pacific eastward as far as Utica lies from the Atlantic. But geography and topography merely make, with the assistance of other factors, those complexes which we call climate and soil. There are, therefore, all sorts of climate from sub-tropical to Arctic,—air which ranges from dripping to dry, water which is sweet and water which is brine, growth which is constant the year round or as regularly periodic as winter and summer in the intemperate parts of the "temperate" zone. There are districts in which the daily range in temperature is greater than the seasonal range, soil which bakes to brick and soil which blows in the breeze, and, in places, light which in. amount and in composition is equaled in few other parts of the known world.
If we summarize these statements we shall see that, so far as plants are concerned, it is the condition and the amount of water in air and soil which is the most striking factor in their environment. Water is not only an indispensable food material and the medium in which all the other food materials enter the plant, but it also regulates the kind and the quantity of light which reaches the earth's surface. By so doing it regulates the prevailing temperatures also, possibly to a greater degree than many of us realize.
Water, a simple, stable compound chemically, we seldom think about, taking it for granted when we have it, grumbling when anything interferes with its supply either in quantity or convenience. The average attitude of civilized man to water is similar to his feeling about the daily newspaper. He thinks little or not at all about the labor of mind and body involved in the regular delivery of the daily paper at breakfast time at Ills front door. And if he thinks of water at all, it is only liquid water, of which he demands a supply ample and safe, at his hand by the turn of a faucet. Yet this flowing water is only a small part of what he needs. The water in the pipes is but a small fraction of the total upon which not only his comfort, but also his very life depends. The water in the soil, brought thither as snow or rain, or by stream and possibly by irrigating ditch, is vastly more necessary than the water in