150 PLANT PHYSIOLOGY 



512, Lecture XL is XXXIX of the 2nd German Edition. 

 1. 33, for nyctitropic read nyctinastic 



1. 37, for nyctitropism read nyctinasty 



513, 1. 5, for nyctitropic read nyctinastic 

 1. 21, for nyctitropism read nyctinasty 



515, 11. 35-7, delete As PFEFFER . . . swelling. 



1. 53, after at the same time, read Less than a second intervened between 

 stimulation and movement. 



516, 1. 16, for hapto- and nycti-tropism read haptotropic and nyctinastic 

 movements. 



1. 20, for excessive read abundant 



1. 45, after movement, read This stimulus-movement may be termed 

 ' seismonastic ' (PFEFFER, Phys.). 



517, 11. 20-4, for The sensitivity . . . need not enter, read Not only in the 

 mode of perception, but also in the rate of reaction, the sensitivity of these 

 plants is closely related to that of tendrils ; hence sensitivity to contact is not 

 sharply distinguished from sensitivity to shocks, and between Mimosa and 

 tendrils as extremes there are many transitional stages. It is impossible for 

 us to discuss all these cases ; we will merely glance briefly at Biophytum, for 

 this plant exhibits many points of interest worthy of note. 



The leaves of this member of the Oxalidaceae are simply pinnate, and 

 a pulvinus occurs at the base of the petiole of each leaf and of each pinna. 

 The latter only, however, are capable of seismonastic movement, by which 

 depression is effected. A few minutes after depression the leaf begins to rise 

 again, but this erection is very soon interrupted in a very remarkable manner, 

 and a renewed depression commences. As this depression is not carried so 

 far, however, and soon neutralized by a second erection, the leaf, after a number 

 of periodic oscillations, reaches again its rest position (DARWIN, 1881 ; HABER- 

 LANDT, 1898). Similar oscillations are also known to occur in the stimulus- 

 movements (e. g. after thermonastic movements) of many Oxalidaceae, e. g. 

 Averrhoa (DARWIN, 1881). 



In conclusion let us briefly glance at the movements seen in the carnivorous 

 plant, Dionaea muscipula, with which may be associated in all essentials 

 Aldrovanda vesiculosa. The lamina of Dionaea consists of two semicircular 

 half-blades, which are united medianly by an articulated mid-rib, and whose 

 margins are fringed with peculiar teeth. On the upper surface of each half- 

 lamina arise three long bristles, each with an articulation at its base. When 

 one of these bristles is touched the leaf closes instantly, the upper surfaces 

 approximating and the marginal teeth interlocking. The curving necessary 

 to effect this movement takes place more especially in the mid-rib or in its 

 immediate neighbourhood. As yet it has not been determined whether the 

 cause of the curving is due to a relaxation of cells or whether it is a growth 

 phenomenon. It would be remarkable if the latter were true, because, as 

 a rule, growth curvatures arise from contact, while shocks give rise to con- 

 traction curvatures. In Dionaea we have undoubtedly to do with a shock 

 stimulus, for a stream of water or a moist gelatine rod is able to effect stimula- 

 tion. Further, the whole leaf surface, both upper and under side, is com- 

 petent to receive such a stimulus, and not the sensitive hairs only. Again, 

 the rapid transmission of the stimulus from the point of application of the 

 stimulus to the motile zone is worthy of note. This plant still requires most 

 careful investigation (Literature in PFEFFER, Phys. ', FITTING, 1905). 



1- 33. after in pairs, read As a rule this phenomenon is limited to the single 

 secondary petiole ; only when the leaf is especially sensitive is the movement 



