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, 0, H 2 O, and CO 2 

 to work with. The first 

 step in the process seems 

 to be the extraction of the 

 C atom from the CO 2 and 

 its addition to the H 2 O 

 molecule thus: 



C0 2 + H 2 O = CH 2 (formic 

 aldehyde) + 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 O 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 6 (monosaccharide) 

 formed by a rearrangement of atoms to make a more 



FIG. 28. Water cultures of Fagopy- 

 rum esculentum. I. In nutrient solution 

 containing potassium; II. in nutrient 

 solution without potassium. Planta 

 reduced to same scale. (After Nobbe.) 



