236 PHYSIOLOGICAL BOTANY. 



had figured in my Plates (part I, pi. i, fig. 4/5). There 

 was no appearance of the formation of one cell (secondary 

 cell) from another (parent-cell), and the inner sac remained 

 unaltered, still forming an inner sac, and certainly not 

 becoming external. This is what ensues during the 

 growth of the cells in the parts of the Phanerogamia. 

 The phenomena which occur in the embryo- sac, or in the 

 cells of the Algae, which, as the remarkable phenomenon 

 seen in the cells of the Spirogyra show, perform different 

 functions from the cells of the Phanerogamia, do not 

 belong here, and no conclusion can be drawn from these 

 so-called cells as regards the cell properly so called. 

 The apices of the roots and leaves which do not grow, 

 consist of very short cells, all of which contain a nucleus 

 of considerable size ; this, however, as in the other cells 

 of the leaf and root, never becomes developed into a 

 distinct cell. 



On the Penetration of the Cuticle into the Stomata. By 

 H. v. MOHL. Bot. Zeit., 1845, p. 1, and Ann. and Mag. 

 of Nat. History, vol. xv, p. 217. The different state- 

 ments which have been made upon this subject induced 

 the author to institute some investigations upon it. For 

 this purpose he adopted the method of soaking the 

 sections of the leaves for examination in tincture of 

 iodine, washing them with water, and then submitting 

 them to the action of sulphuric acid. The latter not 

 only heightens the yellow tint of the cuticle when coloured 

 by iodine, but it has especially this advantage, that the 

 cells of the epidermis of most plants are disintegrated, 

 with the production of a blue colour, or entirely dissolved, 

 according to the strength of the acid employed, and the 

 cuticle can then be very readily distinguished and separated 

 from them. The general result obtained from these in- 

 vestigations was, that, as asserted by Payen, a direct 

 prolongation of the cuticle penetrates into the stomata, 

 and runs down between the cells bordering the orifice to 

 the air-cavity, in the form of a tube very highly com- 



