ELECTRICITY AND PLANT-GROWING. 71 



In the coleus leaf, however, there are two somewhat distiuct 

 effects of the naked light which obscure each other. The leaf is 

 injured by the process described above, aud it may also lose its 

 color. We soon found that some varieties of coleus- are not 

 bleached, but the upper epidermis simply becomes glossy by 

 exposure to the naked light. Microscopic examination shows that 

 those specimens which lose their color, hold the color pigment in 

 the upper epidermis alone, and that it is extracted by the collapse 

 of the epidermal cells, and the chlorophyll of the interior cells is 

 exposed, causing the leaf to become greenish. Iresine (or 

 Achyranthes) is one of those colored plants which hold the color- 

 ing matter in the interior of the leaf, and it is not bleached by the 

 electric light. Knowing these facts, we are able to prognosticate 

 with some certainty what plants will be injured in color by the arc 

 light, for those which have the color distributed through the tissue 

 aud which are, therefore, not discolored, are, normally, nearly or 

 quite as deeply colored on the under side of the leaf as on the 

 upper side. 



If the electric light exerts such profound effects upon the 

 physiological processes of plants, we need not be surprised if it 

 produces anatomical modifications. Bonnier is the only person 

 who has investigated this subject. His experiments were directed 

 to both trees and herbs grown under the influence of electric light 

 run continuously with little aid from the sun, aud the same light 

 run for a part of the day only. His conclusions as to the behavior 

 of trees are as follows : 



"1. We can produce, by a contiuuous electric light, consider- 

 able modifications in structure of the leaves and young stems of 

 trees. 



"2. We can produce a condition in which the plant respires, 

 assimilates, and transpires both day and night in an invariable 

 manner. The plant then seems to be so much affected by this 

 continuous light that the tissues take on a more simple structure. 



" 3. The intermittent electric light (twelve hours of darkness in 

 the twenty-four), produces in the various organs a structure which 

 approaches more nearly the normal structure than that produced 

 by the continuous light." 



His conclusions upon the structure of herbaceous plants are 

 these : 



"1. When the continuous electric light, under glass, produces 

 in an herbaceous plant a large growth, with intense green color, 



