1 54 Journal of Agricultural Research vol. xx, no. a 



number of starch grains present, and thus by this simple means anyone 

 may observe in the twigs of trees and shrubs the gradual disappearance 

 of their starch as spring approaches. 



The measurement of the increasing amount of sugar is more difficult 

 and must be done by chemical analysis. Through the courtesy of the 

 Chief of the Bureau of Chemistry, exact data can be presented on this 

 point from analyses by Mr. Lorin H. Bailey. In samples of dormant 

 blueberry wood taken in early spring when growth was about to begin 

 the ratio of sugar to starch proved to be seven times what it was in 

 similar dormant wood taken in autumn. 



I desire at this time to comment on the fact that one of my colleagues 

 reading the manuscript outline of this address criticized the use of the 

 word "stimulate" as applied to the effect which chilling produces on 

 these dormant plants. His idea was that the chilling induced certain 

 physiological changes in the cell contents but that the actual stimulation 

 to growth came from the temperatures that followed the chilling. I 

 defend, however, the propriety of the language I have used, for although 

 the later stages of growth admittedly can not take place without warm 

 temperatures, not only does the transformation from starch to sugar 

 take place at the chilling temperature but the buds actually swell and 

 push if the chilling temperature is continued for several months. In 

 illustration I may cite the following experiments. 



On March 3, 191 5, 286 cuttings were made from dormant outdoor 

 blueberry plants. They were stored in bundles, some in moist sphagnum 

 moss, others in moist birch sawdust, at a contemplated temperature of 

 31 ° F., just below freezing. The cuttings remained in cold storage until 

 December 6, a little more than nine months. An examination of the 

 cuttings on that date showed that one or more buds had begun to swell 

 on every cutting with the exception of a small number which were 

 mildewed and dead. In other words, growth had already begun to take 

 place at the cold-storage temperature. The thermograph record for the 

 278 days was as follows: 



Hours. 



29 to 32 F 5, 591 



32°to33°F 990 



33 to 34 F 91 



The temperature record did not go above 34 F. It is an astonishing 

 fact that temperatures so very near freezing will start dormant plants 

 into growth. 



On March 3, 1915, 58 cuttings from dormant, outdoor blueberry plants 

 were placed in moist birch sawdust in commercial cold storage at 33 to 

 36 F. On December 4, nine months later, buds on every cutting had 

 begun to grow. Not one of these cuttings gave a starch reaction when 

 tested with iodin. The transformation of their stored starch into sugar 

 was complete. (See PI. 24.) 



