CELL-FORMATION. 141 



each containing one of them inclosed in its centre. The 

 portions of contents are symmetrically arranged around 

 the centre. The parent-cell divides by parietal cell-for- 

 mation into from jive to eight cells with the central nuclei. 

 The process described occurs only in the formation of 

 the special parent-cells in the sporangium of the four- 

 spored Cryptogamia, and in anthers. The modification 

 given under A, I have observed in Florideae, Mosses, and 

 Phanerogamia ; the modification B#, in Florideae, Mosses, 

 Ferns, Lycopodiacea3, Rhizocarpeae, and Phanerogamia; 

 the modification B, in Phanerogamia. 



6. In one parent-cell, or in two connected by conjuga- 

 tion, the whole of the contents unite into a globular or 

 ellipsoidal mass, which is transformed into a free cell by 

 the formation of a membrane on its surface. Here refers 

 the reproductive cell-formation of the Zygnemacese. Most 

 probably, a central nucleus lies inside the contents, this, 

 however, is in any case different from the primary nu- 

 cleus of the one, or those of the pair of cells. 



7. New nuclei originate in a parent-cell, its primary 

 nucleus becoming dissolved ; each of these collects generally 

 a very small portion of contents around it, which become 

 coated by a membrane. The cells originate by free cell- 

 formation in the contents of the parent-cell. Here be- 

 long the formation of the germ-cells in some Algae, in 

 many Fungi, in the Lichens, and the formation of the 

 endosperm-cells in the Phanerogamia. 



8. A cell grows out into a branch, and divides by pa- 

 rietal cell-formation into two cells, in such a way that one 

 corresponds to the original cavity of the cell, the other to 

 the expanded part. Here are to be enumerated the for- 

 mation of branches in Algae, Fungi, Floridese, &c. It 

 exists probably in all plants, but may be recognised best 

 in the organs composed of rows of cells. The origin of 

 the cell-nuclei, and their participation in the cell-forma- 

 tion, is not yet certainly made out. It seems to me that 

 the two following modifications exist, in respect to this : 



A. The expanding cell possesses a central (primary) 



