552 EDMUND NEWTON HARVEY 



dissociated in dilute solutions, there are characteristic specific 

 differences, as a comparison of Ba and Na will indicate. These 

 two substances differ markedly in toxicity even though they both 

 fail to pass the cell surface. 



On the other hand, Barratt's conclusion is not in accord with 

 the observation of Paul and Kronig ('96) who found Na, Li, and 

 KOH equally toxic to bacterial spores and NH4OH less so. 

 Loeb ('97) also found that the increase in weight of muscle 

 caused by Li, Na, K, Sr, and Ba hydroxides depends on the 

 OH ion concentration. 



As previousl}^ stated the power of penetration, in general, bears 

 no relation to the toxicity except among the strong alkalies which 

 fail to enter until the cell is fatally affected. Among the 

 weak alkalies NH4OH enters most rapidly yet is less toxic, than 

 methyl or dimethyl amine. 



The most apparent relation is between the rate of entrance atid 

 the degree of dissociation. The weak alkalies enter rapidly, the 

 strong verj^ slowly. N(C2H;,)40H is an excellent confirmation 

 of the rule. A priori it was to be expected that the tetra-alkyl 

 substitution product of NH4OH would behave just as its primary, 

 secondar}^, and tertiary derivatives. Tetraethylammonium hy- 

 droxide should enter cells rapidly yet such is not the case. The 

 substitution of four C2H0 groups for four H atoms gives a sub- 

 stance whose degree of dissociation may be compared with the 

 strongest inorganic bases, Na or Ba. Correspondingly its power 

 of penetrating cells is likewise limited and comparable with that 

 of Na or Ba. 



The general relation between the dissociation or chemical re- 

 activity of the alkalies and their power of penetrating cells sug- 

 gests that, while we appear to be studying cell permeability, we 

 are in reality confronted with phenomena of reaction velocity, 

 depending on the strength of the base. NH4OH may appear to 

 penetrate readily, because, being a weak base, it combines with 

 the cell proteids less rapidh' and so ma\^ affect the neutral red. 

 NaOH appears to meet a resistance because it combines readily 

 with the cell proteids as it enters and cannot affect the neutral 

 red. But in both cases the proteids must be acted upon before the 



