148 IIOfMEISTEll, ON 



of the leaf, which in Polytrichum, for instance, attains a 

 length of twenty-four cells, the apex is the youngest, the 

 base the oldest portion. In most cases the cells of the 

 base of the leaf-rudiment multiply actively, by which 

 means the leaf acquires its ultimate number of cells. Then 

 the cells of the base of the leaf are relatively younger than 

 those of the apex. 



The naked ends of those branches which are destined 

 to bear fruit change the conical form of the vege- 

 tative bud into a flattened hemispherical one. Many 

 of the cells of its upper surface grow out into short, 

 papillae (PI. XIX, fig. 1). Each of them divides by a 

 septum inclined to the horizon ; the upper one of the 

 newly formed cells divides by a septum perpendicular to 

 that already formed and inclined in an opposite direction. 

 In the terminal cell of the cellular body, which makes 

 its appearance above the surface of the bud, the divi- 

 sion is continually repeated by septa inclined in dif- 

 ferent directions (PI. XIX, fig. 1 ; PL XX, fig. 1). The 

 cells of the second degree, except some of the lower, 

 oldest (from two to six in number) cells, divide soon after 

 their formation by radial vertical septa. Thus, in a short 

 time, there is formed in the space surrounded by the 

 youngest leaves, a number of short, cylindrical, cellular 

 bodies, composed of four vertical rows of cells, intermixed, 

 in many of the mosses, with long multi- cellular hairs, 

 which have originated in the division by transverse septa of 

 certain of the papillate superficial cells of the bud. These 

 clavato- cylindrical masses of cells are the first rudiments of 

 the archegonia as well as of the antheridia. 



When the young archegonium has attained a height of 

 from six to eight cells, all the cells belonging to one of the 

 four perpendicular rows of cells of which (irrespective 

 of the base and the growing apex) it consists, divide 

 by septa parallel to the chord of the arc of the free, arched, 

 outer wall, and cutting the side walls of the cell at an angle 

 of about 45°, by which means the mother-cell is divided into 

 an outer four-sided, and an inner three-sided cell. Each 

 one of the newly-formed cells of the third degree (which 

 form the continuation upwards of the string of diagonally- 



