ROTANICAL GAzer Le 
DECEMBER, 1894. 
‘Contribution to the comparative histology of pulvini and 
the resulting photeolic movements.* | 
FRED DE FOREST HEALD. 
WITH PLATE XXXIV. 
Since the work that I have already completed upon the 
_ comparative histology of pulvini and ‘the resulting photeolic 
‘Movements is too extended to permit of presentation in 
‘these pages, the large mass of details in connection with each 
Species will be passed over, and only an outline of the work 
' Carried out will be here attempted. The complete paper will 
be published elsewhere later. 
4 Aim of study. 
_ Inasmuch as the majority of investigators have busied them- 
Ives with seeking an explanation of the movement of leaves 
ith motor organs without paying very great attention to 
eir histology, the literature dealing with the structure of the 
ulvinus is comparatively scanty. The present work was 
ndertaken as a contribution to the comparative histology of 
Motor organs, hoping that a better knowledge of their struc- 
ttre might aid in understanding their physiology. 
he work that I have already done seems to indicate that 
_Presence of motor organs is much more general than was 
rst supposed. Not only the material collected, but ob- 
ations in connection with the field work confirm this opin- 
n. It remains for further study to reveal to what extent the 
Pposition is correct. 
‘connection with the anatomy of the or 
__ Sive a general idea of the positions which the leaves as- 
®'at nicht. It was not considered necessary to mcasth™ 
tthe €xact angles which the petioles form with the axes nor 
angles of the leaflets with the rachis in the diurnal and 
1 : ; iscon- 
-oiaahe a thesis for the degree B.S. in Botany, University of Wisco 
94. j 
organs Lhave sought 
3—Vol. XIX —No. 12. 
