Influence of Carbon Dioxide. 191 



oxidizing agents failed, whether solutions or emulsions in water 

 were used. Lubimenko^ finds, however, that both carotinoids and 

 xanthophylloids exist which are intermediate between xanthophyll 

 and carotin. The carotinoid from the aril of Euonymus is indeed 

 insoluble in petrol ether, while xanthophylloids are soluble to a 

 greater or lesser extent. According to Lubimenko, in the absence 

 of oxygen, the xanthophyll decreases and the carotin increases, 

 while in boiled leaves exposed to air and peroxidase, the carotin is 

 converted into a yellow pigment equally soluble in alcohol and 

 petrol ether, and with a spectrum intermediate between carotin 

 and xanthophyll. 



The influence of the absence and presence of carbon dioxide. 



Mustard seedlings were grown in moist air in diffuse daylight, 

 and under similar conditions in air deprived of carbon dioxide. 

 The cotyledons in the first case were larger, broader and more yel- 

 lowish green, and in the second were smaller, darker and more 

 bluish green. The cotyledons with the upper halt of the hypocotyl 

 were removed, and the crushed material after killing by boiling was 

 extracted with successive poi'tions of absolute alcohol, and finally 

 with hot alcohol. The last extraction was nearly pure carotin, and 

 showed clearly that the seedlings grown in tlie al)sence of carbon 

 dioxide contained more carotin than the others. 



The whole extract was divided into three parts. From one the 

 chlorophyll was separated by three successive petrol ether extrac- 

 tions, and the amount of chlorophyll estimated by comparison with 

 solutions of known strength. The second sample was evaporated to 

 dryness, dissolved in a minimum of cold absolute alcohol, saponi- 

 fied and separated with ether. The third sample was saponified, 

 petrol ether added, and then water. After w^ashing the petrol 

 ether and ether solutions, their strengths were estimated by com- 

 parison with solutions of known concentration. This method is not 

 wholly accurate, but in the complete separation of chlorophyll, caro- 

 tin and xanthopliyll, the losses are so great that the exact estima- 

 tion of the amounts originally present is impossible. 



The values obtained were : — 



Weight of 



Material. Chlorophyll. Carotin. Xanthophyll. 



wramnies. grammes. grammes. grammes. 



CO2 present - 100 - 0.474 - 0.11 - 0.15 

 C0„ absent - 100 - 0.271 - 0.275 - 0.12 



1 Compt. Rend. 191.5, p. 27S. 



