METEOROLOGY CLIMATOLOGY. 



615 



cold and excessive heat and retards the evaporation of moisture from 

 the soil. 



Experiments on the influence of different solar rays on the color of 

 plants were continued with the same plants experimented with in pre- 

 vious years (E. S. R., 10, p. 112), and with other species in addition. 

 It was found that the different colored rays had different effects, both 

 on the coloration of the plants and on the odor. As a rule plants grown 

 in red light were much more fragrant than those grown in other colored 

 rays. This was quite marked in the case of crassula, which when 

 grown in the open air was almost without fragrance, but when grown 

 in red light developed a delicate perfume resembling that of the 

 banana or amyl acetate. 



Studies of the coloration of the different plants indicated that this is 

 almost always a chemical phenomenon. The coloring matter of the 

 plants was extracted with alcohol and the solution tested with hydro- 

 chloric acid, ammonia, alum, etc. The results obtained are given in 

 the following table : 



The colors of different flowers and their behavior with chemical reagents. 



The author concludes that the action of light on the plant sets free a 

 certain amount of acid which acts on the leucites, producing a red 

 coloration. An illustration of the possibility of modifying the color of 

 plants is afforded by the case of hydrangea, the flowers of which are 

 greenish yellow when they first appear and become rose colored under 

 the action of light. In order to obtain blue hydrangea flowers garden- 

 ers are accustomed to water the plants with a solution of alum. It is 

 very probable that the double sulphate of aluminum and potassium 

 neutralizes the acid and converts the red color into blue. 



A record is given of the temperatures recorded by a standard ther- 

 mometer and by maximum and minimum thermometers. These data 

 are discussed at some length. 



The author concludes that there is no relation between the phases 

 of the moon and the character of the weather. 



In pursuance of a systematic plan for studying the relatiou between 

 clouds and various atmospheric phenomena the author has made a 

 series of cloud photographs, the method pursued in this work being 

 described at some length. 



