352 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



and 0.4 per cent, of organic matter; and, therefore, that 0.5 

 per cent, of organic mineral matter was sufficient to give this 

 plant a definite form, and a texture which enables it to resist 

 atmospheric agencies. 1 B, April 21, 1872, 35. 



INFLUENCE OF VARIOUSLY COLORED LIGHT ON VEGETATION. 



As the result of a series of experiments upon the influence 

 of variously colored light upon vegetation, Dr. Bert has ar- 

 rived at the following conclusions : 1. That green light is al- 

 most as fatal to vegetation as darkness ; 2. That red light is 

 very detrimental to plants, though in a less degree than green 

 light ; 3d. That, though yellow light is far less detrimental 

 than the preceding, it is more injurious than blue light; 4. 

 That all the colors, taken singly, are injurious to plants, and 

 that their union in the proportion to form white light is nec- 

 essary for healthy growth. 



The author has examined the transmitted light from the 

 leaves of various plants, and finds that there is a slight dif- 

 ference in the rays which different leaves absorb and utilize ; 

 and this, he believes, explains the fact that certain plants 

 flourish in the shade of trees, while others will scarcely ex- 

 ist ; in the former case it is supposed that the rays required 

 by the plant are not absorbed by the leaves of the trees, but 

 in the latter they are. 21 A, March, 1872, 261. 



RELATION OF RECENT NORTH AMERICAN FLORA TO ANCIENT. 



The reports recently published by Dr. Hayden of his ex- 

 plorations in Montana contain a great deal of very valuable 

 information, bearing not only upon the present condition of 

 the country, but upon the geological changes through which 

 it has passed. In an account of the results of an examination 

 of certain tertiary fossil plants collected by Dr. Hayden, Mr. 

 Lesquereux, of Columbus, Ohio, remarks upon the typical anal- 

 ogy of our present flora with that of the tertiary. This anal- 

 ogy he finds to become more evident as his researches are 

 multiplied. 



A large number of the genera to which the trees and shrubs 

 of Northern America at present belong have been recognized 

 as tertiary fossils. Among these, in addition to those previ- 

 ously mentioned, are the mulberry (Moms) and the Virginia 

 creeper (Ampelojisis) ; and among the few modern forms not 



