DR. M. J. SCHLEIDEN ON PHYTOGENESIS. 293 



Horkel discovered them in all these many years ago; Baxter 

 only noticed and published their occurrence in Salvia verbenacea. 

 I can add to these Dracocephalum Moldavica. 



R. Brown discovered them in the parenchyma of the pericarp 

 in the Casuarmcs ; and I have met \a ith them in the spongy in- 

 flated cellular tissue of Picridium vulgare, occurring generally 

 in a reticular form, and presenting an exquisitely beautiful ap- 

 pearance. 



Horkel also discovered them in the epidermis of the seed itself 

 in the Polemoniacece long before Lindley made known their pre- 

 sence in Collomia linearis. They occur in Collomia, Gilia, Ipom- 

 opsis, Polemonium, Cantiia, Caldasia, and perhaps in the entire 

 family, with the exception of Plox, to which genus Leptosiphon, 

 in which are the first indications of them, is closely allied. 

 Horkel had also studied them on the seeds of Hydrocharis, 

 where they occur in the highest state of development, long before 

 Nees von Esenbeck published this fact. Rob. Brown makes 

 mention of them in the Orchidea, which statement I find con- 

 firmed as to most of our native species of Orchis. Moreover I 

 have discovered very beautiful spiral fibrous cells in the epidermis 

 of the seed of Momordica elaterium, and a more reticular fibrous 

 formation in Linaria vulgaris, Datura Stramonium, in Salvite 

 and in several other Labiates; probably it is common to the whole 

 family. 



Lastly, they occur, according to Horkel's discovery, in the pa- 

 renchyma of the seminal integuments 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, highly interesting general results 

 will be found in both ways. The general and essential fact at 

 which we first arrive is, that the fibres are never formed free, 

 but in the interior of the cells ; and that the walls of these cells 

 in the young state are simple, and generally very delicate. M. 

 Corda's statement respecting spiral cells without enveloping 

 membrane {Ueber Spiralfaserzellen, &c., p. 7 and 8) is founded 

 merely on inaccurate observation. 



These cells in the commencement are usually filled with starch, 

 rarely with mucus or gum. The starch always passes into the 

 latter state, in the progress of development ; and this is con • 

 verted into gelatin, and, as it seems, gradually from the exterior 

 towards the interior. This gelatin finally passes at its outer 



VOL. II. PART VI. U 



