CHAP. I. LOTUS. 35 



north-east window ; it bent very little towards it, as the hypo- 

 cotyl which was left free was rather old, and therefore not highly 

 heliotropic. A filament had been fixed to the midrib of one of 

 the cotyledons, and the movement of the whole seedling was 

 traced during two days. The circumnutation of the hypocotyl 

 is quite insignificant compared with that of the cotyledons. 

 These rise up vertically at night and come into close contact ; so 

 that they may be said to sleep. This seedling was so old that a 

 very small true leaf had been developed, which at night was 

 completely hidden by the closed cotyledons. On Sept. 24th, 

 between 8 A.M. and 5 P.M., the cotyledons moved five times up 

 and five times down; they therefore described five irregular 

 ellipses in the course of the 9 h. The great nocturnal rise com- 

 menced about 4.30 P.M. 



On the following morning (Sept. 25th) the movement of 

 the same cotyledon was again traced in the same manner 

 during 24 h. ; and a copy of the tracing is here given (Fig. 25). 

 The morning was cold, and the window had been accidentally 

 left open for a short time, which must have chilled the plant ; 

 and this probably prevented it from moving quite as freely as 

 on the previous day ; for it rose only four and sank only four 

 times during the day, one of the oscillations being very small. 

 At 7.10 A.M., when the first dot was made, the cotyledons were 

 not fully open or awake ; they continued to open till about 9 A.M., 

 by which time they had sunk a little beneath the horizon : by 

 9.30 A.M. they had risen, and then they oscillated up and down ; 

 but the upward and downward lines never quite coincided. At 

 about 4.30 P.M. the great nocturnal rise commenced. At 7 A.M. 

 on the following morning (Sept. 26th) they occupied nearly 

 the same level as on the previous morning, as shown in the 

 diagram : they then began to open or sink in the usual manner. 

 The diagram leads to the belief that the great periodical daily 

 rise and fall does not differ essentially, excepting in amplitude, 

 from the oscillations during the middle of the day. 



Lotus Jacobceus (Leguminosse). The cotyledons of this plant, 

 after the few first days of their life, rise so as to stand almost, 

 though rarely quite, vertically at night. They continue to act in 

 this manner for a long time even after the development of some 

 of the true leaves. With seedlings, 3 inches in height, and bear- 

 ing five or six leaves, they rose at night about 45. They con- 

 tinued to act thus for about an additional fortnight. Subse- 

 quently they remained horizontal at night, though still green, 



