Chap. IV. 



DICOTYLEDONS. 



235 



of tlie two terminal leaflets, wliicli were 14 inch in length ; and 

 the movements of one of them were traced during 48 h. (see 

 Fig. 101). The course pursued is closely analogous to that oi 

 ths whole leaf. The zigzag line between 8.30 a.m. and 3.30 p.m. 

 on the second day represents 5 very small ellipses, with their 



Fig. 101. 



lO'JSTja.t 



M'SO'tLmev 



io'40'a.m- 4" 



Vicia faia: circumnutation of one of the two terminal leaflets, the main 

 petiole having been secured, traced from 10.40 A.M. July 4th to 10.30 A.IB- 

 6th. Apex of leaflet 6| inches from the vertical glass. Tracing here 

 reduced to one-half of original scale. Temp. 16°-18° C, 



longer axes differently directed. From these observations it 

 follows that both the whole leaf and the terminal leaflets undergo 

 a well-marked daily periodical movement, rising in the evening 

 and falling during the latter part of the night or early morning ; 

 whilst in the middle of the day they generally circumnutate 

 round the same small space. 



