CELL-FORMATION. 13? 



terminate. In general, the rule may be stated, that in 

 vegetative cell-formation only two cells are formed from 

 one parent-cell, in reproductive cell-formation, on the other 

 hand, the number varies from one to an indefinite quantity, 



i/ / _Z / ' 



and that here the smaller numbers (1, 2, 4, 6, 8) are con- 

 stant, while the larger numbers (5 to 100, or more,) vary. 

 In the first place, as to vegetative cell-formation, from 

 comprehensive researches in the Algae, Fungi, Lichens, 

 Florideae, Mosses, Charas, in the vascular Cryptogamia 

 and the Phanerogamia, I believe I am justified in ven- 

 turing to express, as an universal law, that here always two 

 secondary cells originate in one parent-cell, or, in other 

 words, that one cell divides into two. Views and repre- 

 sentations opposed to this I am compelled to regard as 

 certainly incorrect.* 



In reproductive cell-formation, the cells originate in 

 various numbers in the parent-cell. One cell is found 

 constantly in the formation of the germ-cell of the Zyg- 

 nemaceae, and several other Algae and Fungi, also in the 

 formation of spores and pollen-cells in the special parent- 

 cells. Two, four, six, or eight cells are formed constantly 

 in one cell in the formation of the germ-cells of several 

 Algae, many Fungi, of Lichens, also in the formation of 

 the special-parent-cells of the Florideae, Hepaticae, Mosses, 

 Ferns, and Lycopodiaceae. The number varies from two 

 and four to eight in the formation of the special-parent- 

 cells of Phanerogamia. The secondary-cells originate in 

 indefinite quantity in the formation of the germ-cells of 

 many Algae and Fungi, and in the formation of the endo- 

 sperm-cells in the embryo-sac. 



The position of the secondary cells in the interior of 



* Thus Schleiden and Vogel figure three young cells in an epidermis-cell 

 which has grown out into a hair. (Beitrage z. Entw. der Bluthenth. bei d. 

 Legumin., Act. Acad. C. L. C. N. C. xix, 1, pi. x, fig. 38.) Schleiden also 

 represents three secondary cells in a parent-cell from the terminal shoot. 

 (Beitr. z. Anat. d. Cacteen ; Mem. de 1'Ac. Imp. des Sc. de St. Petersbourg, 

 Ser. vi, t. iv, pi. viii, fig. 9.) In both the places named I have satisfied 

 myself that only two cells are formed in a cell ; that when, however, one of 

 the latter quickly divides again, the appearance may readily be mistaken for 

 three cells originating in one parent-cell. See pp. 119, 120. 



