366 HOtfMiiiSTER, ON 



of spore-mother-cells are produced than in those which 

 form macrospores ; the spore-moth er-cells of the latter are 

 considerably larger. The spore-mother- cells, both after 

 and before their individualization, exhibit a very distinct 

 large nucleus. By degrees the outline of the latter becomes 

 fainter ; at last the nucleus vanishes after two flatly-spherical 

 accumulations of granular matter have made their appear- 

 ance between its periphery and the inner wall of the cell (PI. 

 LIII, fig. 9). After the disappearance of the membrane of 

 the primary nucleus the above accumulations of mucilage 

 immediately assume an ellipsoidal shape, and appear as two 

 secondary nuclei (PL LIIT, fig. 11). Sometimes the spore- 

 mother-cell now divides by a transverse septum, after the 

 constriction of its contents at the equator (PI. LIII, figs. 

 10, 12), and each of the two halves after the dissolution of 

 their ellipsoidal nucleus, and the appearance of two globular 

 daughter-nuclei is divided into two daughter-cells having 

 the form of quadrants of a sphere (PL LIII, figs. 15 17). 

 Sometimes, however, the two secondary nuclei of the mother- 

 cell are dissolved before the commencement of the division 

 of the cell ; four tertiary spherical nuclei appear (PL LIII, 

 figs. 13, 14), and the cell divides at once into four daughter- 

 cells. This latter case is bv far the most uncommon one. 

 At their first appearance the four nuclei usually lie in one 

 plane, and the four daughter-cells of the mother- cell (the 

 special-mother-cells) retain, as in the first case, the form of 

 quadrants of a sphere. It is only very rarely that the 

 special-mother-cells are arranged in the angles of a tetra- 

 hedron. The septa by which the special-mother-cells are 

 separated are of a gelatinous nature. They swell up easily 

 and quickly in water. If their contents are made to contract 

 by the application of diluted acids, the cell walls swell up 

 into a mass simliar to that into which the contents contract. 

 The special- mother-cells of the small spores separate very 

 shortly after their formation. When separate they retain 

 their three-edged (rarely six-edged) form. Now, for the 

 first time by analogy to the similar phenomenon in Equi- 

 setum there is produced in each special-mother- cell a 

 daughter-cell, whose form exactly corresponds with that 

 of the special-mother-cell. The daughter-cell becomes 



