1916 Langdon; on Carbon Monoxide 245 



and nascent hydrogen. In his experiments the nascent hydrogen was 

 formed by the action of the potassum hydroxide on a metallic alloy. The 

 potassium hydrogen carbonate, formed by the interaction of the potassium 

 hydroxide and carbon dioxide, is reduced by the light to formic acid, 

 which, in turn, gives formaldehyde, with the subsequent condensation to 

 sugars. An outline of the steps suggested is shown by the equations: 



CO^+HaO-^HaCOg 

 HX03+KOH^KHC03+H20 

 aKHCOg+light-^K^COg+HCOOH+O 

 HCOOH+light^HCHO+0 



The required presence of potassium hydroxide in Stoklasa's experiments 

 is of interest in view of the fact, previously mentioned, that Nereocystis 

 and some other marine plants selectively absorb large quantities of potas- 

 sium salts from the sea water. 



Spoehr (8) shows that carbon dioxide can be reduced to formic acid by 

 light and that under conditions such as exist in the plant leaf, formic acid 

 will form sugar-like substances. He is not ready to announce a "formic 

 acid hypothesis'" but considers that the process of photosynthesis is one 

 of extreme complexity, the chemistry of which is as involved as that of 

 fermentation and enzyme action. 



The above review, while fragmentary and incomplete, shows that the 

 theories of photosynthesis have been largely concerned with carbon mo- 

 noxide and its reduction product, formaldehyde; and with formic acid, of 

 which carbon monoxide may be considered the anhydride. It therefore 

 seems of interest to raise the question as to whether this occurrence of free 

 carbon monoxide in a living plant is unique in nature or more general than 

 has before been suspected. 



The author has examined gas from the vesicles of Egregia mensiesii, 

 and Fucus evanescens but found no carbon monoxide. The Supply De- 

 partment of the Scripps Institute collected gas from Pelagophycus porra 

 and Macrocystis pyrifera for the author, who found that the former gave 

 evidence of containing a small quantity of carbon monoxide. However, 

 this has not as yet been confirmed and will be more fully investigated next 

 season. In addition, the work is being carried on, to determine if carbon 

 monoxide is present in the air chambers of various land plants. 



