244 
CONTRIBUTIONS TO 
They occur in the epidermis of the pericarp in many Labiatæ, 
as in Ziziphora, Ocymum ; in most Salviœ, for instance, lim- 
bata, hispanica, Spielmanni, &c. ; and lastly, in Horminum 
pyrenaicum. My uncle Horkel was familiar with them in all 
these many years ago; Baxter noticed and published their 
occurrence in Salvia verbenacea only. I can add to these 
Dracocephalum moldavica. 
R. Brown discovered them in the parenchyma of the peri¬ 
carp in the Casuarinœ, and I in the spongy inflated cellular 
tissue in Picridium, vulgare, where they mostly occur in a 
reticular form, and present an extremely beautiful appear¬ 
ance. 
Horkel also discovered them in the epidermis of the seed 
itself in the Polemoniaceæ long before Lindley made known 
their presence in Collomia linearis. They occur in Collomia, 
Gilia, Ipomopsis, Polemonium, Cantua, Caldasia, and perhaps in 
the entire family, with the exception of Phlox, with which 
genus Leptosiphon, in which are the first indications of them, 
is closely allied. Horkel had also studied them in the seeds 
of Hydrocharis, where they occur in the highest degree of deve¬ 
lopment, long before Nees von Esenbeck published the fact. 
Robert Brown mentions them in the Orchideæ, which statement 
I find confirmed as to most of our native species of Orchis. 
I have also discovered very beautiful spiral fibre-cells in the 
epidermis of the seed of Momordica elaterium, and a very deli¬ 
cate reticular formation of fibres in Linaria vulgaris, Datura 
stramonium, in Salviœ, and in several other Labiatæ ; probably 
it is common to the whole family. 
Lastly, they occur, according to HorkePs discovery, in the 
parenchyma of the integuments of the seed in Cassyta and 
Punica. 
Whether these formations be studied in their individual 
development in a single species, or in their progressive stages 
in a series of allied plants, some highly interesting general re¬ 
sults will be obtained in either case. The universal and alto¬ 
gether absolute fact at which we first arrive is, that the fibres 
are never formed free, but are developed in the interior of 
cells ; and that the walls of these cells in the young state are 
simple, and generally very delicate. Cordais statement re¬ 
specting spiral cells without an enveloping membrane (lieber