CHAP. IV. 



DICOTYLEDONS. 



233 



Fig. 99 



the day, it is doubtful whether some of these cases ought not 

 to have been included in the present chapter. 



(7.) Pelargonium zonale (Geraniaceao, Fain. 47). A young 

 leaf, li inch in breadth, with its petiole 1 inch long, borne on 

 a young plant, was observed in the usual manner during 61 h. ; 

 and its course is shown in the preceding figure (Fig. 98). 

 During the first day and night the leaf moved downwards, but 

 circumnutated between 10 A.M. and 4.30 P.M. On the second 

 day it sank and rose again, but between 10 A.M. and 6 P.M. it 

 circumnutated on an extremely small scale. On the third day 

 the circumnutation was more plainly marked. 



(8.) Cissus discolor (Ampelidese, Fam. 67). A leaf, not nearly 

 full-grown, the third from the apex of 

 a shoot on a cut-down plant, was 

 observed during 31 h. 30 m. (see Fig. 

 99). The day was cold (15-16 0.), 

 and if the plant had been observed in 

 the hot-house, the circumnutation, 

 though plain enough as it was, would 

 probably have been far more con- 

 spicuous. 



(9.) Vicia fdba (Leguminosae, Fam. 

 75). A young leaf, 3*1 inches in 

 length, ^measured from base of petiole to 

 end of leaflets, had a filament affixed 

 to the midrib of one of the two ter- 

 minal leaflets, and its movements were 

 traced during 51 h. The filament fell 

 all morning (July 2nd) till 3 P.M., and 

 then rose greatly till 10.35 P.M. ; but 

 the rise this day was so great, com- 

 pared with that which subsequently 

 occurred, that it was probably due in 

 part to the plant being illuminated 

 from above. The latter part of the course on July 2nd is alone 

 given in the following figure (Fig. 100). On the next day 

 (July 3rd) the leaf again fell in the morning, then circumnu- 

 tated in a conspicuous manner, and rose till late at night ; but 

 the movement was not traced after 7.15 P.M., as by that time the 

 filament pointed towards the upper edge of the glass. During 

 the latter part of the night or early morning it again fell in the 

 same manner as before. 



Cissus discolor ; circumnu- 

 tation of leaf, traced 

 from 10.35 A.M. May 

 28th to 6 P.M. 29th. 

 Apex of leaf 8f inches 

 from the vertical glass. 



