PLATE 26 



A. — Dormant blueberry buds stimulated to growth by chalking the stem. This 

 plant was brought into the greenhouse February 4, 1913, to be used in breeding experi- 

 ments. It flowered, but since it had been insufficiently chilled only a few of the 

 uppermost leaf buds on each stem grew. In order to keep small ants from crawling 

 up the stems and interfering with the pollination experiments the stems were chalked 

 near the middle. The dormant buds in and just below the chalked areas started 

 growing. The photograph was taken April 5, the stems being rechalked over the same 

 areas that were originally chalked. After numerous repetitions of the experiment 

 it was found that if the chalking was done lightly the buds would not grow, but if 

 the stems were rubbed hard in the process of chalking, as commonly happened in the 

 case of very smooth stems, the buds grew. It was the hard rubbing, not the chalk, 

 that stimulated the growth. 



B. — Dormant blueberry bud stimulated to growth by rubbing the stem. The 

 photograph, which was taken June 14, 1913, shows a single bud starting into growth 

 on a dormant blueberry plant. The dark area just above the bud is a brown band 

 on an otherwise green stem. It shows the position of a rubbing that was given the 

 stem with a smooth knife handle a few weeks earlier. This bud afterwards grew into 

 a long, vigorous branch, while all the other buds remained dormant. 



