ORIGIN AND FORMATION OF ORGANIC MATTER IN PLANTS. 907 



to explain how organic matter is derived from the product of this 

 decomposition. 



Boussingault demonstrated that when one volume of carbon dioxid 

 is decomposed by the leaves under the influence of sunlight one volume 

 of oxygen results; that is, precisely the amount contained in one 

 volume of carbonic anhydrid. 



Maquenne and the author, in the article already referred to, report the 

 result of studies on the quantities of carbon dioxid absorbed by leaves, 

 taking into account also the quantities which would be absorbed by a 

 volume of water equal to that contained in the leaves under experiment. 

 The results, as already stated, indicated that the absorption is not sim- 

 ple solution of carbonic anhydrid in the water of the leaves, but a 

 chemical combination of the carbon dioxid with water to form the acid 

 CH 2 :! . This carbon dioxid decomposes in the leaves, giving oft" a vol- 

 ume of oxygen (0 2 ) equal to that of the carbonic anhydrid absorbed as 

 observed by Boussingault, and leaving a residue of formic aldehyde 

 (CH 2 0). The fact that formic aldehyde has never been found in plants 

 might be taken as casting doubt upon the correctness of the above 

 hypothesis, but the hypothesis is strengthened by the fact that the 

 molecules of this aldehyde combine easily with each other; and 

 although we do not find formic aldehyde itself we may safely assume 

 that some at least of the bodies present are the result of combinations 

 of molecules of formic aldehyde. As a matter of fact bodies which 

 might be thus formed arc extremely abundant in the vegetable kingdom, 

 as will be seen hereafter. It is known also that the aldehydes combine 

 readily with oxygen and hydrogen and it is of great interest to ascer- 

 tain whether there are not present in plants some products thus derived 

 from formic aldehyde. As a matter of fact such substances have been 

 found. By oxidation formic aldehyde yields formic acid, which gives to 

 nettles their irritating properties. The addition of hydrogen to formic 

 aldehyde in proper proportions yields methyl alcohol, which Maquenne 

 found in all the plants which he studied. 



While the presence in plants of these two compounds so closely allied 

 to formic aldehyde supports the hypothesis of the formation of this 

 aldehyde in the chlorophyll cells at the moment of the decomposition 

 of the carbon dioxid by the sun's rays, there are other proofs of a more 

 convincing nature. The reducing sugars are widely distributed in 

 plants. Loew, and later Fischer, starting with formic aldehyde, have 

 prepared these sugars artificially. They succeeded in linking together 

 six formic aldehyde molecules, and thus formed a reducing sugar resem- 

 bling those found in plants. This beautiful synthesis convinced the 

 physiologists that the primary organic compound from which all the 

 others are derived is formic aldehyde produced by the decomposition 

 of the hydrated carbon dioxid. Many other compounds common in 

 plants are formed by the combination of molecules of formic aldehyde, 

 such as glycerin, which exists in all oils and which contains three 

 molecules of formic aldehyde combined with hydrogen ; the gums, which 



