Page:Microscopicial researchers - Theodor Schwann - English Translation - 1947.pdf/278

244 CONTRIBUTIONS TO They occur in the epidermis of the pericarp in many Labiatæ, as in Ziziphora, Ocymum; in most Salvie, for instance, limbata, 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 pericarp in the Casuarine, and I in the spongy inflated cellular tissue in Picridium vulgare, where they mostly occur in a reticular form, and present an extremely beautiful appearance.

Horkel also discovered them in the epidermis of the seed itself in the Polemoniacee 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 alied. Horkel had also studied them in the seeds of Hydrocharis, where they occur in the highest degree of development, 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 delicate reticular formation of fibres in Linaria vulgaris, Datura stramonium, in Salviæ, and in several other Labiatæ; probably it is common to the whole family.

Lastly, they occur, according to Horkel’s 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 results will be obtained in either case. The universal and altogether 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. Corda’s statement respecting spiral cells without an enveloping membrane (Ueber