2 70 TEE POPULAR SCIENCE MONTHLY 



THE PHYSIOLOGICAL ASPECTS OF CALIFORNIA FOR THE 



BOTANIST 



By Professoe GEORGE J. PEIRCE 



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 intem- 

 perate 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 inter- 

 feres 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 



