70 PLANT PHYSIOLOGY 



during germination with those occurring during autolysis. Such 

 a comparison, however, does not always afford a sufficiently 

 clear picture; for the processes of hydrolysis and synthesis during 

 germination are complicated by the intense oxidation of organic 

 substances due to respiration. For this reason, information 

 concerning the synthetic processes in germinating seeds is less 

 exact and definite than is that concerning the processes of 

 hydrolytic disintegration of protein substances. 



The clearest concept of the changes of a synthetic character 

 during germination has been obtained for carbohydrates. The 

 chief substance utihzed in the process of respiration during 

 germination is glucose, the sugar most frequently found in plants 

 and representing the final product of hydrolysis of more complex 

 carbohydrates. During the germination of seeds in darkness, 

 the chief nitrogen-free reserve substances are starch or other 

 polysaccharides, which rapidly decrease in amount. For 

 instance, according to the observations of Yokum, 3 days after 

 the beginning of germination, 20 per cent of the carbohydrates 

 disappeared from seeds; 6 days later, 35 per cent; 9 days later, 

 63 per cent; and 12 days after germination, 81 per cent. But if 

 the fate of the separate groups of carbohydrates is followed more 

 closely, it will be found that the most rapid decrease 

 occurs in starch, which disappears entirely a few days after 

 germination. The amount of glucose and monosaccharides in 

 general first increases rapidly, then diminishes; while the amount 

 of cellulose increases continuously. This is a consequence of 

 the development of new organs accompanied by an increase in 

 the number of cells and a corresponding increase in the mass of 



cell walls. 



Simultaneously with the transformation of carbohydrates 

 during germination, there is a change in the activity of the 

 hydrolyzing enzymes. The quantitative determinations of 

 Bach and Oparin have shown that if the activity of amylase 

 (diastase) in dormant seeds is expressed by the value 1, 3 days 

 after the beginning of germination it will be equal to 3; 6 days 

 later, 20; and 8 days later, 23. Up to the time when the starch 

 is almost completely dissolved, the activity of diastase increases 

 more than twenty times. But at present, it cannot be definitely 

 stated whether there is an actual increase in the quantity of 

 enzyme, or whether it is the reserve enzyme, activated some- 



