136 VEGETABLE CELLS. 



as, for instance, the Fucoideae and Lichens, a thin-walled, 

 parenchymatous cellular tissue exists at first, and the 

 cells subsequently separate while gelatine makes its ap- 

 pearance between them. In many of the more complex 

 Algae and Florideae I have been able to trace the develop- 

 ment of the organs, step by step, from the firsit cell, and 

 to bring this within definite laws of cell-formation. It 

 thus becomes possible to determine in the perfect tissue, 

 in which parent-cell each cell has originated. But it 

 renders the hypothesis of an intercellular formation of 

 cells wholly impossible. 



Quite recently, Mettenius* has stated that the cells in 

 the ovule and in the anthers of the Rhizocarpese, originate 

 in an amorphous fluid, which is inclosed in a sac formed 

 of a simple layer of cells. My own researches, however, 

 do not agree with this description. I have many times 

 seen a delicate- walled parenchyma during the cell-forma- 

 tion in these organs, and therefore am compelled to believe 

 that the origin of the parent-cells of the pollen in the 

 Rhizocarpese takes place in a similar way to that in the 

 Phanerogamia. In a single organ, namely, in the anthe- 

 ridia of Mosses and Ferns, I am still in doubt regarding 

 the cell-formation, not on account of anything unfavorable 

 to the theory, but because generally nothing at all is seen. 

 It is, besides, to be remarked, that the spermatic vesicles 

 which are formed there are without doubt, utricles ana- 

 logous to cell-nuclei (not to cells), and further, that on 

 the other antheridia (of the Characese and Florideae) no 

 extra-cellular cell -formation takes place. 



The law being established, that in plants both the 

 vegetative and reproductive normal cell-formation takes 

 place only inside parent-cells, the relation of the cell- 

 formation to these parent-cells next demands consideration. 

 The first question is, in what number and what position 

 do these secondary-cells originate in the parent-cell. 



The number of secondary cells is determinate or inde- 



* Beitragc z. Kermtniss der Rhizocarpeen, p. 10 (1846). 



