July 27, 1917] 



SCIENCE 



81 



this vai'iation of the tension of carbonic 

 acid during its excretion. Such consid- 

 erations have strengthened the hypothesis 

 that the hydrogen ion is the true respir- 

 atory hormone. Originally suggested as a 

 guess, this theory has 'been supported by 

 many investigations. But I think that it 

 marks the opening rather than the closing 

 of a chapter in physiology, for the subject 

 is involved in many complexities. 



The whole physiological equilibrium may 

 now be concisely summed up. The hydro- 

 gen ion concentration of the body has been 

 seen to depend upon the ratio 



H-COj 



NaHCO; 



Aeid reacting with this system causes a 

 diminution of the denominator and an in- 

 crease in the numerator of the fraction, the 

 value of the fraction increases, and with it 

 the hydrogen ion concentration. Here- 

 upon the lung reduces the value of the 

 numerator by diminishing the concentra- 

 tion of carbon dioxide in blood and alveo- 

 lar air, the value of the fraction is restored 

 more or less exactly to its original value 

 and with it the concentration of the hy- 

 drogen ion. But the denominator is still 

 below normal. To offset this, there occurs, 

 on the one hand, a production of ammonia 

 which takes the place in the urine of al- 

 kali existing as salt in the blood. This al- 

 kali recomhines with carbonic aeid, form- 

 ing bicarbonate, and thus increasing the 

 denominator. On the other hand, the kid- 

 ney removes less alkali in combination with 

 phosphates than exists in this state in the 

 blood. This alkali, too, helps to regen- 

 erate sodium bicarbonate, and thus to in- 

 crease the denominator. Both of these 

 processes are so regulated that the denom- 

 inator is restored to normal. The con- 

 centration of carbonic acid responds 

 through the activity of the respiratoiy 



mechanism, and the organism returns to 

 its normal state. 



These processes, of course, go on simulta- 

 neously and not in succession. They are, 

 moreover, far less simple than such an 

 analysis admits, for on the one hand the 

 interaction of phosphates and proteins has 

 not been fully described, and, on the other 

 hand, many of these variations influence 

 other conditions and processes in the or- 

 ganism. 



Among these effects are the influence of 

 carbonic acid concentration and of the hy- 

 drogen ion on the affinity of hemoglobin 

 for oxygen and on the volume of the red 

 corpuscles. More general is a necessary, 

 but at present indeterminate, effect on the 

 distribution of electrolytes in the body, on 

 the osmotic pressure, on the state of col- 

 loids, and on the volume. I fully believe 

 that such effects are real and that when 

 acid is produced through long periods and 

 in large quantities in particular organs or 

 tissues, as during diabetes, they may well 

 surpass the direct effects of the simple chem- 

 ical reactions of acid in the pathological 

 complex, and produce a condition very dif- 

 ferent indeed from that of experimental 

 acidosis. For in such conditions the whole 

 physico-chemical composition of the cell, 

 its concentrations and colloidal equilibria, 

 might be sensibly altered. 



But such guesses are one thing and the 

 detailed and very dogmatic speculations of 

 Dr. Martin Fischer quite another. And I 

 feel obliged to say that there is not one 

 particle of evidence for his conclusions, 

 which are indeed inconsistent with, or 

 totally without bearing upon, all the exist- 

 ing quantitative information that we 

 possess upon this subject. 



"Wliat then is acidosis ? Evidently a con- 

 dition lacking necessary connection with 



