Hypothesis of Baeyef. 1 5 5 



The discovery of Butlerow provides the key, and one may 

 indeed wonder that so far it has heen so little utilised by plant 

 physiologists. The similarity which exists between the blood 

 pigment and the chlorophyll of the plant, has often been referred to ; 

 it is also probable that chlorophyll as well as hasmoglobin, binds 

 carbon dioxide. Now when sunlight strikes chlorophyll which is 

 surrounded by CO^, the carbon dioxide appears to undergo the same 

 dissociation, oxygen escapes, and carbon monoxide remains bound 

 to the chlorophyll. The simplest reduction of carbon monoxide is 

 that to the aldehyde of formic acid ; it only requires to take up 

 hydrogen, 



CO + H2=COH2. 



This aldehyde is then transformed under the influence of the 

 cell contents as well as by alkalies, into sugar. As a matter of fact 

 it would be difficult, according to the other opinion, by a successive 

 synthesis, to reach the goal so easily ! Glycerin could be formed by 

 the condensation of three molecules, and the subsequent reduction 

 of the glyceric aldehyde so formed. 



The formation of sugar in a more complicated way is not 

 hereby excluded, and it could very well be possible that plant acids 

 under certain circumstances are transformed into this substance, 

 which in a thousand different forms helps to build up the body of 

 the plant. 



In what manner the cell content acts in order to effect the 

 condensation of formaldehyde cannot be concluded beforehand, but 

 one can assume that the sugar formed remains bound with it, and 

 later, according to circumstances, splits off into carbohydrate, sugar, 

 starch or glucoside. This is exhibited at least in the life-history 

 of the slime fungi in which at a certain stage, from a mass similar to 

 the cell content, a great quantity of cellulose is suddenly different- 

 iated. In this connection it would be very interesting to examine 

 chemically the slime fungi in various periods of their life, and 

 determine whether they contain free sugar or free anhydrides, or 

 whether from the plasmodium sugar or cellulose could be split off 

 in the same way that this takes place in the natural process of 

 development." 



The experimental evidence which has been adduced in support 

 of Baeyer's hypothesis is not of much interest, and in most cases 

 an unjustifiable parallel is drawn between experiments carried out 

 " in vitro " and processes in the cell. So long as our knowledge of 

 the heterogeneous system in which these latter take place is so 



