304 Schively — Contributions to the Life History of 



For the species, the average time occupied is about 1 

 hour and 20 minutes. Darwin 12 records as his most rapid 

 circumnutator among climbing plants — Scyphanthus — which 

 performed a revolution in 1 hour and 17 minutes. Amphi- 

 carpcea monoica must be awarded the palm ; as repeatedly 

 the results of 1 hour, and quite frequently 55 to 51 minutes 

 have been obtained. 



Among tendrils, however, there are more rapid rates 

 reported by Darwin 12 . However, he does not note the 

 length of the circumnutating portion. With Passiflora 

 gracilis, circles are made in as short a period as 57 and 58 

 minutes ; others require longer time ; the average is a little 

 over an hour. A footnote on page 1 54 in "Climbing Plants" 

 calls attention to Passiflora accrifolia, whose tendrils ac- 

 cording to Gray complete a circle in 46 and even 38^ 

 minutes. 



Plants of Amphicarpcea often exhibited a tendency to 

 curve the apex downward, forming almost a complete circle 

 with the part of the stem below. Observations were fre- 

 quently stopped by this occurrence. After remaining sta- 

 tionary, sometimes for several hours, the apex would 

 straighten out and continue its revolutions. No cause could 

 be assigned for this behavior. At times, the circumnutating 

 tip would describe a path, in which the dot recording the 

 place last occupied, would be internal to the continuation 

 of the circle, instead of in line with it. 



The axillary shoots from simple and compound leaves 

 have both been studied. When examined in a normal un- 

 supported condition, they swayed to and fro in wide irregu- 

 lar ellipses, which rarely were complete in form. It was 

 not difficult to discover that circumnutation was very ac- 

 tive, particularly with shoots from the compound leaves. 

 As soon as they were six or eight inches in length, their 

 inclination to twine was manifest, and the apex visibly 

 moved through space. When gently supported, the results 

 were fairly rapid, but the circle was small. The shoots from 

 the simple leaves were not expected to show so much move- 



