author's abstract op this paper issued 

 by the bibliographic service, lune 27 



THE TOXICITY OF ACIDS TO INFUSORIA 



II. THE ROLE OF MOLECULE AND OF IONS 



M. E. COLLETT 



Clark University and University of Buffalo Medical Department 



In the literature on the physiological action of acids there is 

 very little definite evidence as to the role of the anion and the 

 molecule, although it is clear that the activity of many organic 

 acids is not confined to the H ion. Loeb ('13) states that the 

 power of acids to initiate de^'elopment in certain unfertilized 

 marine eggs cannot be due to the H ion, for tartaric, citric, and 

 the mineral acids are relatively ineffective as compared with the 

 fatty acids, nor by the anion, for the sodium salts of the efficient 

 acids (butyric, benzoic, etc.) are inadequate. He therefore con- 

 siders that the action is molecular rather than ionic. Klock- 

 mann ('11) compares the disinfecting action of acetic acid alone 

 and mixed with small amounts of HCl to depress its dissociation, 

 and concludes that the molecule is effective as well as the H ion. 

 Van Dam ('18) in studying the souring of whey, finds that the 

 organisms are fairly resistant to the H ion (they continue to grow 

 up to 11.5 X 10 ~^) and to Na-lactate (up to 0.1 M), but are very 

 sensitive to the undissociated lactic acid molecule. Thus, when 

 sodium lactate is added to the culture in varying, non-toxic 

 amounts, though the final pH varies from 5.3 to 1.8 X 10~^ the 

 final concentration of the undissociated lactic acid produced 

 does not vary. Aside from these three papers, I have found no 

 definite discussion of the question.* 



In the present series of experiments the problem is approached 

 from two directions and a study is made of the toxicity to Para- 

 mecium and Euplotes of several organic acids used both alone 



* Recently Dr. M. H. Jacobs has found that the toxicity H2CO3 as compared 

 with other acids is due to the extraordinary ability of its molecule to pene- 

 trate living tissue. 



67 



