THE PERMEABILITY OF CELLS 



533 



TABLE 4 

 Effect of NHiOH on red Elodea leaves. Glass distilled water used. Solutio7is in corked bottles 



CONCENTRA- 

 TION OF 

 NH4OH 



Normal leaf.. Instantly 1 minute 1 minute IJ minute:3 minutes 6 minutes Not entire- Unaffected 



ly yellow after 1 

 after 30 ; hour, 

 minutes j Slightly 

 affected 

 I after 18 

 hours 



Chloroform 

 treated leaf . I Instantly, instantly! f minute i 1 minute 



3 minutes 



6 minutes 



Dye diffuses: 

 out of leaf 



In Spirogyra, entrance of ammonia may be indicated also by 

 the precipitation of tannin, and this method has been used by 

 Overton ('97) who found that ammonia, the primary and secondary 

 amines penetrate readily, the tertiary amines and quaternary 

 ammonium bases do not, behaving in this respect hke inor- 

 ganic hydroxides. So far as I have observed trimethyl amine 

 enters cells readily but not so quickly as the methyl or dimethyl 

 derivitives of ammonia. 



f If an Elodea leaf has remained in a solution of to NaOH (or 

 K, Ca, Sr, Ba, N (€2115)4 hydroxides of any concentration) until 

 the color change to yellow has occurred, and then is immediately 

 placed in pure water it is found that the leaf has been killed and 

 the red color never returns.^ The capacity of again accumulat- 

 ing dye is likewise lost. The entrance of a sufficient quantity of 

 inorganic alkah to affect the neutral red produces irreversible 

 changes in the cells themselves. 



But if a similar Elodea leaf is placed in an tt NH4OH solution 

 the color change occurs almost instantly (about one minute). 

 Furthermore, on transferring to pure water, the red color in the cells 

 and the protoplasmic rotation characteristic of the plant returns. 

 Evidently death of the leaf does not necessarily ensue from the 



' Except on immediately adding an acid. This shows that the dye is actually 

 changed to yellow and not reduced to a colorless substance. The actual yellow 

 color may be obscured to some extent by the green chlorophyll present. 



