REACTIONS OF CRAYFISHES. 



with propinquus in carbon dioxide and comparing the ratios of 

 the increased concentrations at the high acid concentration end 

 with the concentration at the low end of the low temperature 

 experiments, it will be seen that there is no definite relation 

 between the two. This comparison may be objected to on the 

 grounds that propinquus was intoxicated by the carbon dioxide, 

 but by turning to the acetic acid experiment, where propinquus 

 w r as not affected there is seen the same variation between the 

 ratings and Weber's ratio. At the same time it will be seen that 

 there is a more definite relation between the rating and the 

 total concentration of the acetic acid. In general the lowest 

 total concentrations of acids have the lowest ratings. Experi- 

 ments 15 and 1 6 are exceptions but still the range is not wide as 

 compared with the great variation of Weber's ratios. 



Now turning back to the carbon dioxide experiments (Table 

 III., Expts. 2, 26 and 5) the intensities of the reactions are in 

 reverse proportion to Weber's ratios, but are in direct proportion 

 to the concentrations of the carbon dixoide solution used in 

 the experiments. In the hydrochloric acid experiments (see 

 Chart II. and Table III., Expt. 39 and 47) the intensity of the 

 reactions conform with Weber's ratio, but at the same time it 

 conforms with the concentrations of the hydrochloric acid used. 

 Thus it is seen that the total concentration of the acid determines 

 the intensity of the reaction. In other words the intensity of 

 the reaction varies directly as the hydrogen ion concentration. 

 This view is supported by comparing the ratings of the carbon 

 dioxide and acetic and hydrochloric acid experiments. It is seen 

 by comparing the carbon dioxide and acetic and hydrochloric 

 acid experiments (see Table III.) that the rating on an average 

 of the hydrochloric acid experiments are highest, acetic acid 

 next and carbon dioxide lowest. This is due not to the higher 

 molecular concentration of the hydrochloric acid over that of 

 the acetic acid, since the molecular concentrations of the acetic 

 acid were higher than that of the hydrochloric acid (Tables I. 

 and II.), but to the higher ionization of hydrochloric acid over 

 that of acetic acid and acetic acid over that of carbon dioxide 

 in solution, thus giving higher ion concentrations. 1 These same 



1 Stieglitz's table of the ionization constants of acids, 1911. 



