( ^34 ) 



lengtl] of from 3 — 6 em. The petiohiles are V'a millimeler lonpj, nillior 

 thin, nearly without hairs, with small articulations. The leafstalk 

 and the common rachis are nearly bare or xery short-haired. Both 

 are, also after irritation, almost horizontal. Hy day in non-iri-itated 

 state all the leaflets are always in snch a jwsition that the midrib 

 of each leaflet is standing almost vertically on the secondary i-achis, 

 the blade beinj; normally and horizontally expanded. Hence, in 

 nnirritated diurnal condition all the leatleis are Ivin!»' iiearlv in the 

 horizontal plane. 



As to the movements provoked on 4 and 5 February in the above 

 experiment plant of Poincidiwi rey'ia by mechanical agency (shaking 

 and tap|)ing) I refer to Plates 1 and 2 and further to the following 

 observations. 



E X f) 1 a n a t i o n o f t h e j» 1 a t e s o f P o i n c i a n i a r e g i a. 



Pl((te 1. The foresaid plant in non-irritated state photographed at 

 9.40 a.m. on 5 Fcbruai-y 11)11. 



Plate 2. The plant ligui-ed on Plate 1, 5 minutes later (9.45 a. m.) 

 after irritation by vigorous shaking. The exterior of the ])lant has 

 quite changed within 5 minides in consecpience of the mechanical 

 irritation, and this is most ob\ious when the [)lant is consitlered tVom 

 above. By the stimidation the leaflets have in the fii'st place 

 performed a rotation aiound their longitudinal axis with the result 

 that the left half of each leaflet is turned obliquely dowjiwards, 

 the right one obliquely upwards. Secondly the leaflets make 

 simultaneously another irritation movement. Of all the leaflets, namely, 

 the tops move almost at the same time, or at least in very (piick 

 succession, sideways in horizontal direction so that, owing to this 

 second movement the midrib of the leaflets, which primitively was 

 at right angles with the secondary petiole, now is at acute angles 

 with it. After this complex movement, performed \vithiu 5 minutes, 

 all the leaflets are standing obliquely upright, clog- wheellike, whilst 

 in consequence of the inclined position of their midrib the two leaflets 

 of each pair have taken the shape of the letter V and have their 

 faces almost parallel. 



Further o b s e r \' a t i o n s on the above plant of 



P o i n c i a n i a r e g i a photographed on 



5 F e b r u a r y. 



5 February, 4.30 p. m. — The plant has outwardly quite reco- 

 vered from the stimulation (of 9.40 a. m.) and all the leaflets are 



