28 CHEMISTRY OF PLANT LIFE 



THE PRODUCTION OF SUGARS AND STARCHES 



The next step in the process, the conversion of formaldehyde 

 into sugars and starches, is not necessarily a p/iofosynthetic one, 

 as it can be brought about by protoplasm which contains no 

 chlorophyll or other energy-absorbing pigment. It is, however, 

 a characteristic synthetic activity of living protoplasm. There 

 is little definite knowledge as to how the cell protoplasm accom- 

 plishes this important task. As has been pointed out, the polym- 

 erization of formaldehyde into a sugar-like hexose, known as 

 " acrose," can be easily accomplished by ordinary laboratory 

 reactions, and acrose can be converted into glucose or fructose by 

 a long and difficult series of transformations. But such processes 

 as are employed in the laboratory to accomplish these artificial 

 synthesis of optically-active sugars from formaldehyde can have 

 no relation whatever to the methods of condensation which are 

 used by cell protoplasm in its easy, almost instantaneous, and 

 nearly continuous accomplishment of this transformation. Fur- 

 thermore, these simple hexoses are by no means the final products 

 of cell synthesis, even of carbohydrates alone. In many plants, 

 starch appears as the final, if not the first, product of formalde- 

 hyde condensation. At least, the transformation of the simple 

 sugars, which may be supposed to be the first products, into starch 

 is effected so nearly instantaneously that it is impossible to detect 

 measurable quantities of these sugars in the photosynthetically 

 active cells of such plants. Other species of plants always show 

 considerable quantities of simple sugars in the vegetative tissues, 

 and some even store up their reserve carbohydrate food material 

 in the form of glucose or sucrose. Attempts have been made to 

 associate the type of carbohydrate formed in cell synthesis with 

 the botanical families to which the plants belong, but with no 

 very great success. For each individual species, however, the 

 form of carbohydrate produced is always the same, at least under 

 normal conditions of growth. For example, the sugar beet always 

 stores up sucrose in its roots, although under abnormal conditions 

 considerable quantities of raffinose are developed. Similarly, 

 potatoes always store up starch, but with abnormally low tem- 

 peratures considerable quantities of this may be converted into 

 sugar, which becomes starch again with the return to normal con- 

 ditions. 



