TENSION PHENOMENA OF LIVING ELEMENTS. 123 



easily to Xa than to Ca. It is plasmolyzed by .2. M CaCl- 2 and 

 not by the isosmotic .2<)M NaCl but by .$x.\f XaCl. .195. I/ 

 CaClo and -375.1/ XaCl just failed to plasmolyze. On mixing 

 100 c.c. -375-^f XaCl with 10 c.c. .I95J/ CaCl 2 , thus decreasing 

 the osmotic pressure of the former, marked pla-mol\ -.-is occurred. 

 Thi- indicates that Ca decreases the permeability to Xa. 1 From 

 further work by the same author, not yet published, it appears 

 th.it N.i increases and Ca decreases the permeability of certain 

 marine plants. Also Fluri 2 obtained increase in permeability by 

 salt- of .ilnniinium, yttrium and lanthanum. 



I >' \rir-, plasmolyzed cells of Tradescantia, containing blue 

 (i-ll sap, \\ith 4 percent. KXO 3 solution, then added nitric acid 

 until tin- color changed to red. The acid made the cells pcr- 

 i- \ K\U 3 for they regained their turgor and linally bur-i. 



i- explain- the easy penetration of acids into n-11-. I'tViin 

 found ihat if red beet cells, petals of Pitlmonariu, Manu-n hair- 

 oi Track 'tuitia and other anthocyan-containing cell- are placed 

 in extivmelv dilute HC1 or H-jSO.,, they suddenK- turn red. in- 

 diiatinii iniinediate penetration of the acid. It allo\\cd t<> re- 

 main Inn a short time, the cells are not killed, and tin- color 

 ( lian^c i- 1 1 -versed on returning the tissues to acid-free water. 



I have n- pealed these experiments, using cells of n-d Uii, 

 ii d i.ibb.ige and red nectar glands of Vicia _,'/;'</, and tind that 

 mineral ai id> penetrate, but that (the lipoid soluble acetic acid 

 penetrates much nion- rapidly and also more easily alters the 

 jila^nia membrane, causing pigment to diffuse out, if not can- 

 tii>n-l\ applied. Alkalis also penetrate, but 'the Lipoid soluble) 

 ammonia penetrates much more rapidly than the oiheis. Am- 

 monia doi-> not so easily increase the permeability t<> the pi^mt-nt 



a- dor- arctic acid. 



Kuhlaiid 1 after staining root hairs of Triancn, etc., \\ith tin- 

 indicators, methyl orange and neutral re<l, found that mineral 

 acid- a- well as lipoid soluble acids penetrated. 



1 Tin- \\oik .-I Ki.irney, Report 71, U. S. Dept. of Agriculture, indicates that 

 (a prevents tli<- pl.i-molytic and toxic effect of MK. Imt thU i 



follou illi; <!i.Mth. 



* Flora i - XCIX.. 81. 



3 "(KiimtUchc Untersuchungen," Leipzig, 1877, p. 135. 



*Jnlirb. u-iss. Bot.. 1908. XLVL. r. 



