The Intake of Carbon 207 



photosynthesis with different intensities and quantities 

 of light, with varying quantities of CO 2 (up to the satura- 

 tion point of water), at various temperatures, etc. 



112. The formation of sugar and starch. - With respect 

 to the formation of organic food-material it has been indi- 

 cated in the brief outline of the course of photosynthesis 

 that glucose is generally regarded as the first stable result. 

 The formation of glucose and free oxygen from carbon 

 dioxid and water constitutes a complex process, but the 

 reaction is commonly expressed in the following conven- 

 tional manner : - 



6 CO 2 + 6 H 2 O = C 6 H 12 O 6 + 6 O s . 



Some years ago the view was advanced by Von Baeyer 

 that formaldehyde is an early step in the reduction of the 

 carbonic acid, and that then six molecules of the formalde- 

 hyde, H . COH, become linked together or condensed to 

 form a hexose sugar, C 6 H 12 6 . Recent work along many 

 lines strengthens this conception of the process, and it 

 seems to have been demonstrated (although there are some 

 criticisms of the method) that by artificial experiments 

 with the factors light, chlorophyll, and C0 2 , formaldehyde 

 may be produced, although in small amount as compared 

 with the quantity which must result from photosynthesis. 

 The details of this work, however, and the criticisms 

 thereof do not require consideration. 



It is difficult to picture simply all possible relations of 

 the glucose which may appear as the first stable product, 

 but the accumulation of this substance in the cell leads to 

 the formation of other sugars, especially bioses (C 12 H 22 On) 

 and ultimately to starch, a complex molecule having the 

 general formula (C 6 H 10 5 ) H . 



