Meyen's Report for 1839 on Physiological Botany. 249 



XXXII. — Report of the Results of Researches in Physiological 

 Botany made in the year 1839. By F. J. Me yen, M.D., 

 Professor of Botany in the University of Berlin*. 



[Continued from p. 137.] 



M. Schleiden t> in a treatise on the spiral formations in the 

 cells of plants, has collected together the results both of former 

 observations and also of his own. His views respecting the 

 metamorphoses of the spiral tubes are certainly for the most 

 part correct : he says, " The layers which are deposited upon 

 the primary structureless cellular membrane have in every 

 case, at their first appearance, a regular arrangement which 

 may be made evident in different ways, and a spiral band or 

 fibre as their foundation, and from this basis all the different 

 forms of the walls of the so-called vessels and cells are de- 

 veloped 5 but the one cannot be considered as a stage of trans- 

 ition to the others." M. Schleiden then gives a view of the 

 phaenomena which occur during the growth and metamor- 

 phoses of the cells of plants. In the first period, the simple 

 membranes which form the cell increase throughout their 

 whole substance by true intersusception ; but whether the 

 same kind of growth takes place at a later period could not be 

 determined, although in some cases it cannot be denied that 

 it is so. Now the deposition of new layers on the inner sur- 

 face which follows is in the form of one or more spiral closely 

 wound bands, and M. Schleiden thinks that from some as yet 

 imperfect observations, he may conclude that originally two 

 such bands at least occur, which correspond to the ascending 

 and descending streams of the gummous formative substance. 



According to M. Schleiden' s views, it is from these second- 

 ary deposits that all the various formations of the walls of 

 cells and vessels proceed according to the influence of the 

 following causes : — 



1. Either the cell has or has not reached its full extension 

 when the secondary deposits commence, and upon this ap- 

 pears to depend the production of the spiral vessels and of 

 the porous formations. Then are mentioned the different 

 cases which may occur during the formation of the spiral 

 fibres, and from this is derived the production of different 

 forms of simple and metamorphosed spiral tubes. Here how- 

 ever many statements are put forward, which partly contra- 

 dict existing observations, and which partly open a wide field 

 for discussion. 



* Translated and communicated by Henry Croft, Esq. 

 f Flora von 1839, pp.321— 334 and 337— 344. Translated in our Journal, 

 vol. vi. p. 35. 



