456 M. E. COLLETT 



In the other acids (formic, tartaric, HCl, etc.) lowering the 

 temperature either lessens the toxic action slightly or leaves it 

 quite unaffected. Butyric and acetic, however, are more toxic 

 at 15° than at 20° and still more toxic at 10°. Indeed, they are 

 almost as toxic at 10° as at 30°. If they consistently become 

 more toxic with falling temperature throughout the range 30° 

 to 10°, this might be explained as due to rate of adsorption, 

 since this is a process favored by low and diminished by high 

 temperatures. But this cannot be the case, since at 20° they 

 are less toxic than at 30°. Probably some further processes are 

 involved, such as solubility, etc. A striking example of this 

 sort has been described by Hans Meyer (quoted by Lillie, '16). 

 The solubility of ethyl alcohol and chloral hydrate is increased 

 by rise in temperature, while the solubility of salicylamid and 

 monoacetin is decreased, and corresponding with this difference 

 in solubility is the fact that the narcotic power of the former 

 group is increased by rise in temperature, that of the latter 

 decreased. Such conditions apparently complicate my results. 



It appears from these experiments that temperature defi- 

 nitely influences the toxic action of acids. The degree of influ- 

 ence, however, varies with the acid, its concentration, the organ- 

 ism, and the temperature chosen. These irregularities show 

 that the action is by no means simple and that it probably 

 involves both physical and chemical factors.^ 



D. Importance of the H ion 



The general order of toxicity obtaining in equinormal solu- 

 tions gives some indication of the mode of action. Full data are 

 given in table 1 and graph 1. The order runs: HCl > dibasic 



1 Lillie ('17) found that long exposure to sea-water at 2° to 6° would suffice 

 to initiate development in starfish eggs, and that the rate of activation in butyric 

 acid is greater at 6° than at 8° to 10°. These results are not strictly parallel 

 with those obtained in the present experiments upon cilia, in which the lower 

 temperatures (10° to 15°) increase the effectiveness of butyric acid, although 

 alone they are not effective; but in both series of experiments Doctor Lillie's 

 explanation seems applicable, viz., that a change in the physical condition of the 

 structural colloids due to cold may alter their permeability or other properties 

 and so affect their resistance to certain reagents. 



