52 Prof. Lindley upon the Genus Decaisnia. 
cause of the movement to excitable globules contained in the 
fluid of what he calls the cylindrenchyme of the stigma; this 
fluid being carried to the extremities of the cylindrenchyme, 
these extremities are dilated, which causes the stigma to bend 
in one direction ; but when the stigma is touched, the globules 
and the liquid flow back to the bottom of the cylinders, and 
in this case, this side becoming the longest, the style erects 
or bends in an opposite direction: M. Morren therefore re- 
fers the cause to the excitability of a vital fluid. 
In examining the stigmata of Diplacus puniceus and the 
different species of Mimulus, in order to ascertain if they con- 
tained any analogous structure to that described by M. Mor- 
ren, I found the inner surfaces of the stigmata in all com- 
posed of elongated cylindrical cells, the ends of which are free 
and prolonged into tapering jointed glandular hairs: these 
hairs, which thickly clothe the surface of the stigma*, are di- 
lated at the extremities, and at the base where they arise each 
one forms a thickened elbow, with the cell of which it is the 
termination. 
When the plates of the stigma are in their natural position 
these hairs are erect, but on examining them after the plates 
had collapsed, I found them gathered together into bundles 
of a dozen or more with their points drawn closely together, 
and in some cases twisted spirally round one another : in the 
stigma of Mimulus roseus each hair was recurved over its own 
cell. It is easy to conceive that such a movement of the hairs, 
forming as they do the extremities of the cylindrical cells, 
would cause the stigma to incline inwards, and it is probable 
that the natural cause of their movement is, as M. Morren 
asserts, the reaction of an excitable fluid. 
I am, Sir, your obedient Servant, 
JosEPH HENDERSON. 
Milton, near Peterborough, July 13, 1840. 
VII.—A Note upon the Genus Decaisnia, Ad. Brong. By 
Professor LinpDLEy. 
Tus genus, founded upon a Brazilian plant from the Island 
of St. Catharine’s, was published by M. Adolphe Brongniart 
in the Botanical part of Duperrey’s Voyage. It was admitted 
into the Neottideous tribe of Orchidacez in my Natural Sy- 
stem of Botany, and by Endlicher has been equally adopted 
as a genus of the drethuseous tribe. 
* In the stigma of Goldfussia anisophylla these hairs are shorter, more 
thickly crowded together, and less dilated at the points than in stigmata of 
Mimulus and Diplacus. : 
