74 CARNEGIE INSTITUTION OF WASHINGTON. ' 



The three native species showed an ability to increase their resistance to 

 water-loss with increasing aridity, and thus appeared to obey Le Chatelier's 

 theorem, which states "Each change in an outer condition that affects a body 

 or system produces in it a change in such a direction that as a result of this 

 change the resistance of the body or system to this outer change is increased." 

 The cultivated plant did not show this phenomenon, but the system was 

 destroyed, since the plant died under the more arid conditions. Thus, here 

 appears the beginning of the application to biology of a law which has already 

 been found to be universally true both in physics and chemistry. 



The results of investigations of stomatal movements and the lowering of 

 leaf-temperature by evaporation show that, while all of these phenomena 

 aid in bringing about resistance to increasing aridity, they are not sufficient 

 to account for the marked increase in resistance to water-loss shown with 

 increasing evaporating power of the air. 



For each species of the plants, a number approaching a constant was 

 obtained when the ratio T/EXS was calculated, T representing the trans- 

 piration per unit area for a 24-hour period, E the loss from an atmometer 

 for the corresponding period, and S the water-content of the soil per 100 

 grains of dry weight. Thus it appears that transpiration varies with both 

 the evaporating power of the air and the soil water-content. 



A comparison of the daily and of the seasonal water-content of plant parts 

 with the transpiring power of the plants shows that the amount of water 

 in the plant undoubtedly influences the rate of transpiration. That is, when 

 the water-content of the plant is lowered, the capillary and colloidal imbibi- 

 tional forces become greater. 



The appearance of a physical constant for the physiological behavior of a 

 given species under different conditions and the very apparent obedience of a 

 biological process to a general physical law are the most interesting results 

 obtained from the work. 



Strand Vegetation of the Pacific Coast, by William S. Cooper. 



During the summer of 1922, field work in the Monterey region was practi- 

 cally completed. In a continuation of the study of the ancient dune area 

 bordering Monterey Bay, east and northeast of Monterey, in which the 

 detailed vegetation map begun in 1919 was finished, the limits of the dune 

 region were determined and also the relations of the dunes to the underlying 

 geological formations. Four permanent quadrats, established in 1919, were 

 recharted. The most obvious changes noted were continued destruction of 

 pioneer vegetation by both erosion and deposition in an active blowout area; 

 notable increase of dune shrubs, especially Lupinus chamissonis, on the lee 

 slope of a stagnant sand trail; increase of Lupinus and Arctostaphylos pumila 

 on an ancient dune area burned over 7 years ago; and slackening growth-rate, 

 as compared with previous years, of a large prostrate plant of Arctostaphylos 

 pumila 5 meters in diameter. A portable apparatus for photographic record- 

 ing of quadrats 1 meter square, making reproductions of such areas on a scale 

 of one-tenth, was constructed and used for the first time in the above studies. 



Particular attention was given to exploration of the dune areas of the 

 Monterey Peninsula, and some important divergences in the successional 

 processes from those occurring along Monterey Bay were discovered. The 





