BOTANY OF TIIE CEYLON PATANAS. 329 
the stem, on its lower (dorsal) side. At the same time the 
leaflets fall independently, until they hang downwards in a 
vertical plane, the dorsal surfaces of opposite leaflets being in 
contact. In the sun-position, the leaflets are bent downwards 
as in sleep, but the rhachis, instead of sinking, rises until it 
occupies an approximately erect position (sce diagram). 
SLEEP. SUN. 
Biophytum proliferum. 
Smithia blanda.—In moving into the sleep-position, the leaf 
sinks * upon its pulvinus and the leaflets move upwards and 
forwards until their ventral surfaces are iu contaet with the 
rhachis or with the dorsal surfaces of the more distal leaflets. 
In the sun-movement the leaf was not observed to fall, but the 
leaflets move into approximately the same position as they oceupy 
in the sleep-position, though they are not so tightly closed as in 
the latter case. 
Cassia Kleinii and C. mimosoides.—The leaf-movements in 
these plants are the same as in Smithia blanda, except that in 
C. Kleinii, in the sleep-position, the distal end of the rhachis is 
bent lower than the proximal end and the rhachis is bow-shaped, 
the coneavity being on its dorsalside. These species form an 
exception to the rule in the genus, that the leaflets fall in attain- 
ing the sleep-position T. 
Phaseolus trinervius and Atylosia rugosa.—The sleep-position 
of the leaflets of the trifoliate leaves of these plants is the same 
as that described by Darwin for Phaseolus vulgaris (51). A 
* Cf. the movement in S. Pfundii. Darwin, ‘ Movements of Plants,’ p. 356. 
T The sleep-movements of C, mimosoides are described by Darwin, loc. cit. 
p. 372. 
