288 Schively — Contributions to the Life History of 



grew directly downward. Yet just beside this specimen 

 were plants with many leafy branches which twined upon 

 any available support. 



Truncation Experiments. 



Having observed these phenomena, a series of what may 

 be termed " truncation experiments" were made. These 

 consisted in cutting off the main stem at different levels, 

 and noting the result upon the future development of the 

 axillary shoots. Nearly all of these were performed in the 

 green-house during June and July, a few, however, during 

 the winter months. The results of some of these are stated 

 below. 



I. 



Cutting off Main Shoot above Simple Leaves. 



On June 6, 1896, the main shoot was cut off above the 

 simple leaves ; in the axil of each was a branch one inch 

 long. 



On June 16, both branches had lengthened considerably ; 

 they formed almost a right angle, and were growing up- 

 ward. 



On June 29, the axillary runners were about eight inches 

 long, and although growing upward, had not yet twined. 

 Sticks were placed for them. 



On July 6, the runners were over a foot long, and both 

 were twining. (Plate XXIII.) 



On June 19, the main stem of a plant was cut above the 

 simple leaves ; also all buds from the axils. 



On June 29, additional accessory buds had developed, 



and the shoots were one inch, and one and one-half inches 



respectively. Another bud was appearing in the next axil. 



On July 7, the branches had turned upward, and were 

 three and six inches respectively. The bud remained in 

 about the same condition. 



On July 15, the branches were ten and fourteen inches. 



