CELL-FORM ATION . 119 



different conclusion. In the very first place comes the 

 question, what import may be attributed to those obser- 

 vations which represent the secondary cells free within 

 the parent-cells, as Schleiden's in the germinating spore 

 of MarcJiantia* in the hairs of the ovary of Lupinus,^ 

 in the terminal shoot of Opuntia,\ in the pollen-tube, and 

 in other cells, and my own in the apex of the root of 

 Lilium. || As to my own earlier investigations, they be- 

 long to an epoch (autumn 1841, and spring 1842,) 

 when I was yet unacquainted with the mucilaginous 

 layer. When I discovered it, in the summer of 1842, 

 at Naples, in Algae and Florideae, and subsequently re- 

 found it in other vegetable-cells, I soon became convinced 

 that my earlier researches were doubtful, since that which 

 I had held to be the cell-membrane might in every case 

 have been the mucilaginous layer. 



With regard to the facts published by Schleiden, I 

 likewise believe that the explanation given by him is by 

 no means placed beyond all doubt. In the first place, 

 cell-formation in the pollen-tube cannot prove anything 

 for other cell- formation ; since here two thoroughly dif- 

 ferent kinds of cell-formation, one of which is transitory 

 while the other produces the embryo, have not yet been 

 nearly sufficiently discriminated. The cell- formation in 

 the spore of Marchantia, I must, from certain researches 

 of my own on the germination of the Hepaticse, hold to 

 be incorrect ; and conjecture that a confusion has occurred 

 with the accidental formation of utricles, such as some- 

 times happens in cells. With respect to the rest of the 

 observations published by Schleiden, it must be borne in 

 mind that he also makes no distinction between cell- 

 membrane and mucilaginous layer ; so that the interpre- 

 tation is always possible, that the apparently free secondary 



* Miiller's Archiv, 1838, Tab. iii, figs. 19, 20. 

 - Acta Ac. C. L. C. Nat. Cur., vol. xix, p. 1, pi. x, fig. 38 e. 

 % Mem. de 1'Acad. Imp. d, Sc. de St. Petersbourg, VI Serie, vol. iv, 

 pi. viii, fig. 9. 



Grundz. 2d Ed. pi. i, figs. 12 and 16. 



Linnaja, 



2d Ed. pi. i, figs. 12 and 

 1842, PI. ix, figs. 30, 31. 



