June, 1919] ANNUAL REPORTS. 21 



of samples taken at five periods of vegetation; namely, dormant, buds swelling, 

 in bloom, cessation of active growth, and leaf-fall : 



In the apple tree the carbohydrates are stored in the form of starch and sac- 

 charose. 



At the awakening of vegetation the hydrolysis of starch is more marked in 

 the two-year-old branches and tlu-ee-year-old branches than in other parts of 

 the tree, but is not extensive since the supply of carbohydrate material needed 

 by the growing parts is mainly furnished by the hydrolysis of the saccharose 

 stored in the small roots. 



During the growing season saccharose accumulates in large amounts in the 

 small roots and in noticeable quantities in the two-year-old branches and 

 three-year-old branches, and coincidentally starch storage occiu-s in these 

 same parts. 



Fats are always present in the apple tree and apparently function as re- 

 serve food material since they disappear from the roots during the early 

 stages of growth and accumulat^e in the one-year-old branches and two-year- 

 old branches. 



Reducing sugar is the form of translocation of the carbohydrates. It 

 accumulates toward the awakening of vegetation only in the small roots from 

 which it disappears very largely at the time the tree blooms when it begins to 

 accumulate slowly again until leaf-fall. These variations are due to a trans- 

 location upward to the growing parts, which, after the tree has bloomed, be- 

 come self-supporting and finally contributory of reserve food material to all 

 parts of the tree. Reducing sugar then begins to accumulate in the roots 

 where condensation occurs. 



The nitrogenous reserve materials are stored mainly in the younger branches 

 from which they pass to the actively growing regions upon the awakening of 

 vegetation. 



Ash is present in greater amount in young than old organs. A translocation 

 of ash occurs from the small roots to the one-year-old branches at the awaken- 

 ing of vegetation, but little or no migration takes place from the large roots or 

 the older branches and trunk. As the new gro\\'th develops, the ash acciunu- 

 lated in the one-year-old branches passes into the shoots; and, with the devel- 

 opment of an absorbing root system, the ash constituents enter the tree and 

 their presence becomes manifest by a rise in the ash content of the small roots. 



The phosphorus required in building new tissues at the awakening of vege- 

 tation is mainly obtained from the younger branches. 



The translocation of potassium at the awakening of vegetation is Limited, 

 but occvus mainly from older parts than those that supply the needed phos- 

 phorus and nitrogen. 



The Relation of Potassium to the Growth of the Cereals. 

 The study of the relation of potassiimi to the growth of the cereals, a project 

 which is also co-operative with the Department of Botany, has been carried 

 on continuously with the view to determining at what time in the growth of 

 the cereals the seedhngs require a supply of potassium in addition to that stored 

 in the seed, and also to observe the effects and symptoms of potassium starva- 

 tion on seedhngs of wheat, corn and buckwheat. These seedlings have been 



