68 RESPIRATORY EXCHANGE OF ANIMALS AND MAN 



and unfertilized eggs of sea urchins considerably 20 to 50 per cent 

 in the case of fertilized, 300 to 800 per cent, in the case of unfertilized 

 eggs. 



Hydrogen ion concentration. Changes in hydrogen ion concentra- 

 tion of the sea water may have a very profound influence upon the 

 oxygen absorption of fertilized eggs of sea urchins. When the water 

 is made more acid the oxidations are inhibited while they are greatly 

 stimulated by alkalis. 



TT Relative 



2 Absorption. 



io~ 6 normal 0-36 No segmentation 



io- 8 ,, I'oo Normal segmentation 



io~ u ,, 2*i No segmentation 



Loeb and Wasteneys [1913, 3] have confirmed the result of Warburg 

 with regard to bases, but only in so far as they found that a consider- 

 able increase in alkalinity, which was very harmful to the eggs, had the 

 effect described, while changes in reaction within physiological limits, 

 which they take to be H* = io~ 7 to H- = io~ u , have no effect what- 

 ever. 



THE INFLUENCE OF DRUGS UPON THE RESPIRATORY EXCHANGE OF 



ENTIRE ORGANISMS. 



The influence of drugs upon the respiratory exchange of entire 

 organisms runs parallel in certain cases to that observed on single 

 cells, but more often a parallelism cannot be established owing very 

 probably to the regulating mechanisms brought into play. 



I. (a) Prus sic Acid. Of lipoid-soluble specific substances prussic 

 acid, HCN, and phosphorus have been studied on higher animals. 



The action of prussic acid is very powerful, and it obviously 

 diminishes or destroys the oxidative power of the tissues. Claude 

 Bernard [1857] had made the observation that when an animal was 

 poisoned with prussic acid the venous blood became of a bright red 

 colour which seemed to indicate that the tissues had lost the power of 

 taking up oxygen. A closer study was made by Geppert [1889] who 

 proved that this explanation was correct. After injection of KCN or 

 HCN (i c.c. of 0-25 per cent. KCN per kilogram) a comparatively slow 

 and usually not lethal intoxication is brought about, which is character- 

 ized chiefly by a considerable decrease in the oxygen absorption and also 

 in the carbon dioxide production. The effect on the CO 2 elimination 

 is sometimes obscured, because there is always an increased ventila- 

 tion of the lungs by which CO 2 is washed out (Geppert). At a certain 



