420 



SCIENCE. 



[N. S. Vol. XIX. No. 480. 



solutions and to pure water in which leaves 

 were immersed showed only a very slight 

 penetration of the stain into the glands and 

 other epidermis cells, and none into deeper- 

 lying tissue. Incidentally, the gland cells 

 were found to be much more resistant to 

 plasmolysis than are other cells of the leaf. 

 Hence it is reasonably certain that in the 

 case of Statice, at least, the epidermal 

 glands are not absorbing, but merely excret- 

 ing organs. Their importance to the plant 

 may consist in their enabling it to rid itself 

 of excessive amounts of salt, while second- 

 arily the presence of the salt deposit on the 

 plant is, perhaps, useful in reducing the 

 rate of transpiration from its surface. The 

 question whether under natural conditions 

 the leaf is able to withstand the attraction 

 exerted upon its water content by the solu- 

 tion tension of the excreted salts, remains 

 unanswered. 



The Cardinal Principles of Ecology: Pro- 

 fessor W. F. Ganong, Smith College. 

 The paper comments upon the rise and 

 promise of ecology, points out certain 

 marked defects in its present methods, and 

 discusses the direction it must take in order 

 really to advance in the future. The 

 ecology of the future must be based upon 

 the exact study of environmental physics 

 in correlation with physiological life his- 

 tories of plants. Then the principles 

 underlying the nature of adaptation are 

 discussed, including the reality of adapta- 

 tion, its evolutionary origin, its race (not 

 individual) character, the necessary im- 

 perfection of all adaptation, its metamor- 

 phic phylogeny. This paper is to be pub- 

 lished in full in Science. 



Cinchona in Jamaica as a Botanical Sta- 

 tion (illustrated by stereopticon photo- 

 graphs) : Professor D. S. Johnson, 

 Johns Hopkins University. 

 Cinchona Station, recently visited by the 



speaker, is located on a spur running south- 



ward from the Blue Mountain chain. It 

 is 4,900 feet above sea-level and has a cli- 

 mate that is comparatively dry, cool and 

 stimulating. On the plantation at present 

 are a well-built residence, several buildings 

 fit for laboratories, a greenhouse and a 

 rather extensive garden. The latter eon- 

 tains many introduced alpine and temper- 

 ate-climate plants from many parts of the 

 globe. On the remaining 20,000 acres of 

 the plantation, and in the surrounding 

 regions, are to be found many types of 

 vegetation, varying from the dense forest 

 of the mountains and of the deep river 

 valleys, through many types to the xero- 

 phytic vegetation of the hills and plains 

 south of the Blue Mountains. 



The rich and varied flora, delightful cli- 

 mate, equipment and ready accessibility 

 from all the Atlantic ports of the United 

 States, make together a series of advan- 

 tages such as probably no other location in 

 tropical America possesses. 



The Influence of Differences in the Elec- 

 trical Potential on the Growth of Plants: 

 Professor G. E. Stone and Mr. N. F. 

 MoNAHAN, Massachusetts Agricultural 

 College. 



For many years the idea has prevailed 

 that atmospheric electricity exerts an in- 

 fluence upon plant growth. It is known 

 that vegetation frequently becomes charged 

 with electricity to quite an extent, also that 

 during thunder-storms the potential of the 

 air is likely to be high, and frequently 

 changes from positive to negative. 



Observations made in our laboratory 

 have shown that at a distance of thirty 

 feet from the ground the air is charged 

 positively about 90 per cent, of the time. 

 The differences in potential between the 

 earth and the air ranged in voltage from 

 75 negative to 300 positive. Some of the 

 earlier experiments, carried on in a limited 

 way, seemed to show that when atmospheric 



