148 



Mr. F. Kidd. 



Table VII. — Showing the Eetarding Influence of Increased Concentrations of 

 Carbon Dioxide upon the Eate of Normal Eespiration in Germinating 

 White Mustard Seeds, measured by C0 2 Production and Oxygen Con- 

 sumption.* 





Concentrations 



of carbon dioxide initially present 

 atmospheres. 



in 



per 

 cent. 



10 per 

 cent. 



20 per 

 cent. 



30 per 

 cent. 



40 per 

 cent. 



80 per 

 cent. 



After 14 hrs. cx - C ^ S ain 



58 



48 



38 



33 



26 





17 



c.o. 2 loss 



71 



57 



49 



45 



38 





32 



Respiratory quotient 



-82 



0-84 



0-77 



0'73 



0-69 





0-53 



After 40 hrs. c -°" °S\S ain 



173 



158 



96 



75 



61 





41 



c.c. 2 loss 



197 



185 



122 



104 



97 





90 



Respiratory quotient 



0-87 



-85 



0-75 



0-72 



0-63 





0-45 



Conducted in dim diffuse light. 20 per cent, oxygen present initially in each experiment. 

 15 grm. of seed set dry on 50 c.c. damp sand and 10 c.c. tap water in each experiment. Results 

 obtained from analyses. 



Temperature of experiments 25 '5° C, by thermostat. 



Table VIII. — Showing the Eetarding Influence of Increased Concentrations 

 of Carbon Dioxide upon the Eate of Normal Eespiration in Green Peas, 

 Measured by C0 2 Production and Oxygen Consumption. 





Concentrations of carbon dioxide initially present 

 in atmospheres. 



per cent. 



10 per cent. 



25 per cent. 



... „. , cc. COo formed 



Atter 24 hours 4—: 



cc. (J 2 loss 



. n, .„ , cc. C0 2 formed 



After 43 hours j— — 



cc. C 2 loss 



I 9 = 1-05 

 66 



99 = 1 -07 

 92 



41 



— = -85 

 50 



— = -88 

 85 



51 = -85 

 45 



fi = -84 

 72 



Conducted in dim diffuse light. In each experiment, 15 fully swelled green peas, weight 

 7 "6 grm., removed from testas immediately before. Results obtained from analyses. 

 Temperature of experiment 25 "5° C, by thermostat. 



The above experiments show that the rate of normal respiration in the 

 presence of excess of oxygen is retarded by the presence of carbon dioxide. 

 This is a remarkable result. The values obtained in the experiments of 

 Table VII when plotted give curves similar to those obtained in anaerobic 



* The seeds used in this and other similar experiments with oxygen present obeyed 

 the laws of carbon dioxide inhibition already demonstrated in Parts 1 and II of these 

 researches. 



