TENSION PHENOMENA OF LIVING ELEMENTS. 1 25 



by turgor changes in certain of their cells. Trondle 1 found that 

 light produced changes in permeability of these cells. 



Changes in permeability may not only affect the turgor, but 

 also the assimilation and excretion, and consequently the 

 metabolism and growth of the cells. Chapin 2 observed that 

 ( '), in certain doses is a stimulant to the growth, not only of 

 green pl;mt> but also of moulds. As only ,i few saprophytes can 

 decompo-e ('();, it is not probable thai its effect is nutritive. 

 A ^imilar simulating action of ether and various salts, even 

 such toxic ones as those cf zinc, was previously knoun. These 

 salt-, probably stimulate without penetratini; the cells, since 

 7.\\, lor in-taiice, is not a constituent of protoplasm. ' This 

 one to suppose that the initial effect of .ill of these 

 i- on tip- surface, changing the permeability of the cells. 



Wachter limd that potassium decreases the p'-rmeabilitx of 

 onion i ells. SuL'ar diffused out of sections of Allinm cc{>n placeil 

 in distilled \\ater or hypotonic sugar solutions, but a trace of 

 potassjuin s.ilt entirely prohibited the difliisii.n. When the K 

 \\as n-ino\ed tin- diffusion recommenced. 



Czapek 8 determined increase in permeability by the exosmosjs 

 ol tannin in cells of Echcveria leaves. Various inono\aleni al- 

 c.h..ls and k< tones, ether, ethyl urethan. di and tri acetin, 

 Na-oleate, ohic acid, lecithin and cholesterin all \\.\-\ caused 

 mosjs ,,; i.innin in concentrations (aqueous solutions) \\hich 

 had a siitlacc- tension of about 0.68. It \\ould appear therel'on- 

 that these substances, chiefly of the class ,,| indifferent narcotics, 

 alter ihe cells if tliey diffuse into them, or dilhise into certain 

 Structures -\\c\\ as the cell lipoids or the plasma membrane. 

 It seems more reasonable to suppose that the' plasma membrane 

 is the siructure affected, and the more the substance louers the 

 siirlace teii-ioii of water, the more it diffuses into the plasma 

 membrane, \\hen this membrane is altered, it allo\\~ escape 

 of tannin. Some substances such as chloral hydrate are el lei tive 



; Bot., IQIO. XLVIII.. 171. 



X 



I "<-\>. " I )\ n.uiiii'- i.i' Living Maiti-i," pp. 73, 74. 

 1 J.ii-.i-i- XI. I., 165. 



6 " t 'l.i-r rim- Mrtli.i.lt.- /in ilirekten Bestiininung der OberMchenspannung der 

 ri.i-iiKili.uit \"ii I'll.in/cii/clli-n." Jena, (".. Fi-clitT. 



