THE MODERN POTATO PROBLEM 241 



its storage life is yet to be written, sufficient information 

 is now available to characterize certain fairly definite 

 periods of importance in practical storage. During 

 the early dormant period chemical changes due to ripen- 

 ing may continue, if the tubers have not fully ripened 

 in the ground. These chemical changes consist mainly 

 in the building up of complex food and structural ma- 

 terials from simpler substances. For example, nearly 

 all of the sugar in unripe potatoes is converted into 

 starch. Cork formation in the skins may continue for 

 some time. Shrinkage of the tubers due to loss of water 

 is unusually high during this period. 



The latter part of the dormant period may be spoken 

 of as the late dormant period. By this time the skins 

 are well corked and the loss of water from the tubers 

 by evaporation is very low unless the storage air is 

 unusually dry. The building up and breaking down 

 processes in the tubers now tend to equalize each other 

 and at temperatures between 40 and 70 F. there is very 

 little change in the percentage composition of the tubers. 

 The potatoes are much less effected by storage condition 

 than during any other period in their storage life. 



The period that elapses between the time when 

 potatoes come out of their rest period and will sprout 

 under growing conditions, and the time when sprouting 

 actually begins, may be thought of as the post-dormant 

 period and is the critical period in the storage of po- 

 tatoes. The breaking-down processes, or hydrolysis, 

 tend to predominate, probably due to weakening with 

 age of the constructive or synthetic processes. The 

 tubers are liable to soften rapidly with unfavourable 



