THE MANIFESTATIONS OF LIFE 



89 



be protected. It is possible to follow what are presum- 



ably the successive steps in the formation of one of the 



best-known of the vege- 



table products, starch. 



Thus, in conditions such as 



prevail in the water cul- 



ture, to which reference has 



been made, we have found 



available for use O in the 



air, water (H 2 0) in which 



the salts required are dis- 



solved, and CO 2 in both the 



air and water, in small 



quantities. We have, 



therefore, O, H 2 0, and C0 2 



to work with. The first 



step in the process seems 



to be the extraction of the 



C atom from the C0 2 and 



its addition to the H 2 O 



molecule thus: 



CO 2 + H 2 = CH 2 O (formic 

 aldehyde) + O 2 . 



If we study the metabolism 

 of growing plants photo- 

 synthesis we find that 

 this actually takes place, for 

 in the gases given off there 

 is an increase in the which 

 can only be accounted for 



by the abstraction Of the C 



from the CO 



2 \ . 

 AS the Synthetic process 



is continued we find: 



6CH 2 O = C 6 H 12 O 6 (monosaccharide) 

 formed by a rearrangement of atoms to make a more 



FlG> 28 ._ Water cultures of Fagopy , 



rum esculentum. I. In nutrient solution 

 containing potassium; II. in nutrient 

 solution without potassium. Plants 

 reduced to same scale. (After Nobbe.) 



