PHYSIOLOGICAL BOTANY. 227 



belongs to the secondary layers as it is coloured yellow by 

 iodine, whilst the outer membrane, Hartig's Eustathe, 

 and the intermediate layer, Hartig's Astathe, are not 

 coloured. Hartig must not be offended at my refusing 

 to adopt these technical terms. They are not only per- 

 fectly superfluous, but even retard the progress of science; 

 they form the skins which science must throw off at 

 every moulting period. The inner membrane of the cell, 

 or the membrane of the utricle, belongs, with the spiral 

 vessels, to the secondary formations, and undoubtedly 

 has some relation to the formation of spiral vessels, 

 although not that which Hartig has far too positively as- 

 serted. I shall now immediately pass to 



The Life of the Vegetable Cell, together with its Forma- 

 tion, Growth, Development, and Dissolution. By Dr. 

 THEODORE HARTIG. Berlin, 1844. 4. This memoir 

 requires very careful analysis, which cannot be given in 

 a few words. We shall only make a few remarks upon 

 it here. In the first section The Life of the Vegetable 

 Cell, during the period of Cell-formation, the author says, 

 a, " Origin of cells. Cells are only formed in the inte- 

 rior of a parent-cell. They are originally simple Pty- 

 chodal cells with fluid contents, the cell-sap. In the 

 course of its development, the Ptychode becomes subdi- 

 vided into an inner and an outer Ptychodal membrane, 

 in this manner a Ptychodal space is formed, which is 

 distinct from the cavity of the cell. A fluid resembling 

 the laticiferous fluid, the Ptychodal sap, is secreted in this 

 cavity from the sap of the cell. In the Ptychodal sap 

 the new cell-germ is formed ; this becomes developed into 

 three different kinds of cells, digestive-, propagating-, 

 and colour-cells. The digestive- (Metacard-) cells effect 

 the further elaboration of the sap of the cell. The pro- 

 pagating- (Epigon-) cells develope a new generation of 

 cells, of three different kinds, in their Ptychodal cavity, 

 in the same manner as the original parent-cell. The 

 colour- (Euchrom-) cells form Euchrome (which includes 



