CALIFORNIA FOR THE BOTANIST 271 



the pipe. The soil water, added to by rain and stream, conserved by 

 cloud and fog, is still further preserved, for the plants which receive it 

 into their roots, by the invisible moisture in the air. For the greater the 

 humidity the less the evaporation from soil and living body, from plant 

 and animal alike. Water is always present, wherever there is a living 

 thing, because, in addition to what is taken into the living body, water 

 is formed in the body and in every cell in which respiration is taking 

 place. The liberation of carbon dioxide in plants and animals is but 

 part of the chemical process which is called respiration. Along with 

 carbon dioxide, water also is formed in the oxidation of the carbon com- 

 pounds which form the bulk of our food. This is exhaled, or escapes by 

 evaporation, with the carbon dioxide, or is carried off or used. The 

 character of the organism and the nature of the environment determine 

 the amount and the manner of the loss of water by the body. 



These are all truths of which we become conscious on reflection, but 

 unless contrasting environments are close together, we are not likely to 

 become conscious of them. In the Eocky Mountains one may see the 

 timbered slopes of one side facing the grassy slopes across the valley. 

 On the Pacific coast, chapparal and forest cover the opposing slopes, 

 meeting at the stream-bed and at the head of the narrow valleys between 

 the ridges of the Coast Eanges. Not the fires of the Indians nor the 

 clearings of the whites account for these contrasts, but rather the rela- 

 tions of the opposing slopes to water, its supply and its loss. 



The long valley in which lies the Bay of San Francisco is bounded 

 by ranges of mountains, mainly parallel but strikingly different on the 

 two sides. On the western shore of the Bay, gently rising to the moun- 

 tain rampart which bars the Pacific Ocean from access, forests and denoe 

 shrubby growths, chapparal, cover the still uncleared slopes. The 

 forests are heaviest in the passes, for though the rainfall may be little 

 or no greater there, and the run-off no less rapid, the passes are fog 

 channels. Through these channels the ocean fogs flow, bringing mois- 

 ture and saving moisture in soil and vegetation. The plants of these 

 east and west passes are strikingly different from those of the canons 

 which head into the mountain barrier. In the fog channels one sees 

 the foliage and the luxuriant growths of a humid clime: the closed 

 canons look dry and have drought resisting or short-lived plants except 

 close to the streams, many of which run only for a short time after the 

 rainy season ends. The redwood and the California nutmeg (Torreya 

 calif ornica) may be taken as types of the two localities. The difference 

 is due to water. 



In parts of the world where, over great areas, conditions are similar, 

 and the water supply is regularly much above the minimum requirement, 

 the dependence of plants and animals upon water is much less clear, the 

 influence of water upon them much less evident. There can be no 



