VON BAYER'S HYPOTHESIS 43 



of sugar (glucose) and six molecules of oxygen are 

 formed. The oxygen, which equals the volume of carbon 

 dioxid taken in, is given off to the air. There is good 

 reason to think, however, that this equation merely ex- 

 presses the final result of a series of chemical reactions, 

 the details of which are not now known. The most 

 plausible hypothesis proposed regarding the combination 

 is that of the eminent European chemist, von Bayer. 



VoN Bayer's Hypothesis of Photosynthesis. — 

 According to this hypothesis, first, one molecule of carbon 

 dioxid may be combined with one molecule of water to 

 produce formic acid, with the liberation of one molecule 

 of oxygen; second, this formic acid is reduced to formic 

 aldehyde with the liberation of more oxygen ; and third, 

 the formic aldehyde molecules may combine with one 

 another — may polymerize — so that a molecule of sugar 

 containing six atoms of carbon is produced. The equa- 

 tions concerned are as follows: 



CO2 + H2O = H2CO3 (carbonic acid) 

 H2CO3 = HCOOH + (formic acid and oxygen) 

 HCOOH == HCOH + (formic aldehyde and oxygen) 

 6 HCOH = C6H12O6 (glucose sugar) 



No chemist or physicist has thus far proved by experiment 

 the accuracy of this very suggestive hypothesis, and the 

 field is still open for investigation. 



The Products of Photosynthesis. Foods. — It is 

 certain that a sugar containing six atoms of carbon 

 (CeHiaOe), or a multiple of six (C12H22O11), in the mole- 

 cule is made in daylight in chlorophyll-containing plant 

 cells, and that from this sugar sooner or later all other 

 foods and most of the other products of plants are formed 

 by addition of one or another of the chemical elements 

 found in the different food materials. The food may 

 accumulate as sugar, or it may be stored in insoluble 

 form — temporarily or for longer times — in the form of 

 starch or cellulose, fat, or oil. Nitrogen and phosphorus 



