68 Simons — Comparative Studies on tlie Rate of 



Later in the season, on July i8, August 8 and 15, experi- 

 ments were performed on shoots of Convolvulus Sepium grow- 

 ing in the garden. The plant spread itself, for the most part, 

 along the ground, slender branches, now and then, standing 

 upright and exhibiting a tendency to climb. The times of 

 revolution were as shown in the table appended, the shortest, 

 I hour 1 1 minutes, being longer than the spring time of 57 

 minutes. This plant produces two distinct types of stem, the 

 twining and the prostrate. The latter are of a darker color, 

 more woody, thicker and have stronger tips. Two of these 

 were tied to a support and watched from 8.30 till i. There 

 was no perceptible movement, later a slight one. Nothing 

 further took place before 2.35 p. m., when observation ceased. 

 Three days later no evidence of ability to climb could be 

 noticed, the stems having been left tied to their supports. 



Humulus Lupulus. — Winter buds of the Hop were trans- 

 planted and formed vigorous shoots by February 9, when 

 circumnutation movements were observed during two days 

 (two distinct plants used), with the appended results. 



The periodicity of growth was not so marked in this case, 

 but gave indication of afternoon acceleration, as will be seen 

 by reference to the table. 



Darwin's shortest time for the Hop was 2 hours 8 min- 

 utes, during what he called "hot weather." Our plants were 

 first observed in late winter when i hour 5 minutes was 

 the shortest period. On a hot day (July 15) tips of a 

 plant growing in the garden were protected from wind, sup- 

 ported, and watched under glass ; the time i hour 40 min- 

 utes, was obtained. Another tip made a circle in 2 hours 

 35 minutes, when it seemed to be burnt. On August 16, 

 another tip was tried, with the result 2 hours 14 minutes. 

 Casually observed, the tips do not seem inclined to grow vig- 

 orously in the hot weather. The quick spring movements 

 confirm this. 



Lonicerabrachypoela and Phascolus vulgaris were used in class 



