ACCUMULATION OF EKEfiGY V : 101 



stage, as indicated, is accompanied jt>y/>a^lo6sei/iiig -s) 

 the union of carbon monoxide and hydrogen to form form- 

 aldehyde seems fairly simple. 



2CO 2 >2CO + O 2 ^ 2HrOH , 20 

 2H 2 0-->2H 2 +0 2 > 2HC(J i- 20 *- 



Not only by heat, but also by exposure to ultra violet light 

 can carbon dioxide and water be split in the manner indicated. 

 Therefore it seems probable that formaldehyde was produced 

 before chlorophyll-bearing organisms were evolved.* The 

 formaldehyde can polymerise, in the way to be mentioned 

 shortly, to form carbohydrate. This carbohydrate may have 

 been the source of energy for primitive non-chlorophyll cells. 

 The chlorophyll seems therefore to be a mechanism for 

 absorbing the energy, but it is not necessary for the formation 

 of formaldehyde. 



Formaldehyde, especially in the presence of alkali, readily 

 condenses to form acrose, a hexose sugar, from which other 

 hexoses can be derived. In living organisms the synthesis 

 is asymmetrical, which is probably due to the presence of 

 enzymes. The enzyme seems so closely associated with the 

 protoplasm that it has not yet been made to act outside the 

 cell. The condensation of formaldehyde is slower than the 

 formation of formaldehyde. The formation of formaldehyde 

 probably represents a reversible reaction so that the presence 

 of formaldehyde inhibits its formation. Thus the rate of 

 condensation of formaldehyde regulates the rate of photo- 

 synthesis. 



The further transformations of carbohydrate are interesting. 

 It has been suggested that the first product of synthesis 

 may be cane sugar or starch, but it is more logical to believe 

 that a hexose is formed first, and that this condenses to form 

 di- and poly- saccharides. 



Although formaldehyde is poisonous to cells, experiments 

 have been carried out in which leaves and other portions of 

 plants have been treated with very low concentrations of 

 formaldehyde. Spirogyra is found to assimilate formaldehyde 

 with the formation of sugar, even if it is kept in the dark, 

 but in higher plants light seems to be required for this 

 reaction, f 



The formation of carbohydrate does not entirely depend 

 upon photosynthesis, T)ut; it can be brought about by the use 



* B. Moore and T. A. Webster, Pvoc. Roy, Soc., 1914, B, vol. 87, 

 p. 163. 



f S. M. Baker, Ann. of Bot., 1913, vol. 27, p. 411. 



