THE HIGHER CRYPTOGAMIA. 121 



an elongated, oval cellular mass, consisting of four rows of 

 cells (PI. XV, fig. 16). This arises from frequently re- 

 peated division of the apical cell by means of alternately 

 inclined septa, and by the production of radial longitudinal 

 septa in the cells of the second degree. The cells of one 

 of these rows, with the exception of the two at the base, 

 and the one next to the apex, divide by septa parallel 

 to the longitudinal axis of the antheridium, and. cutting the 

 side walls of the mother-cells at an angle of 45°. The 

 antheridium now consists of a short, central string of cells, 

 surrounded by a single layer, the cells of which are 

 arranged in successive sets of four cells of equal height. 

 The further development, like the preceding, corresponds 

 with that of the antheridium of Anthoceros and Pellia, 

 with this distinction, that the multiplication of the cells in 

 the direction of the longitudinal axis, exceeds that in the 

 direction of the thickness. The ripe antheridium is oval. 

 The apices of the cellular masses which arise between 

 the antheridia expand considerably in breadth as soon as 

 they have outgrown the antheridia. They consequently 

 soon close together over the antheridium, so as to form 

 narrow passages, hardly perceptible from the outside. The 

 cell which covers the air-cavity develops itself into a 

 stomate, exactly in the same way as the median cell of the 

 covering of the air-cavities on the upper side of the recep- 

 tacle (PL XV, fig. 16). The cells adjoining this cell divide 

 by slightly inclined longitudinal septa parallel to the axis 

 of the stomate. The inner of the cells thus produced, 

 which form a ring round the stomate, take part in the 

 formation of the covering of the air-cavity, expanding at 

 the same time in breadth. In the air-cavities in the 

 middle of the antheridial disc these cells divide frequently 

 by longitudinal and transverse septa perpendicular to the 

 outer surface. The cells of the base of the disc grow into 

 the expanding air-cavities, and form chains of cells filled 

 with chlorophyll. When the antheridia are ripe, the cells 

 of the apical, covering layer separate from one another, the 

 internal mucilage, swarming with thousands of active, 

 motile spermatozoa, is forced through the narrow canal at 

 the apex of the antheridia which opens externally, and ap- 



