4 Splachnidium rugosuvi. 



growing epidermal layers. The cells of the meristematic zone lying 

 internally and immediately round the apical cell, divide tangentially and 

 give rise to large filaments ; the young cells undergo division and grow in 

 length, they branch and anastomose repeatedly, so that below the apex 

 there comes to be a filamentous network of cells filled with a dense olive 

 green protoplasm (plate IT., figs. 3 and 4) ; at this stage young lateral 

 filaments are as yet unformed. 



The young cells of the outer epidermal layer, with the exception of those 

 lying directly round the apical cell, give rise to hairs. Each hair is produced 

 as a small protuberance which increases in length, and is finally cut off by 

 a wall ; cell divisions follow till a short filament is produced. The cells of 

 an adult hair are slightly elongated, sometimes the upper members of a 

 filament are spherical or bulge unilaterally, so that the whole hair takes on 

 a moniliform appearance, and the protoplasm which has shrunk away from 

 the wall lies in the centre as an irregular mass (plate II., fig. 4). All the 

 hairs bend towards the apical cell, and it is to be noted that in those which 

 are destined to become moniliform the bulging appears first on the side 

 away from the apex. These hairs are referred to by Mr. Laing as being 

 possible antheridia.* 



The apical cell persists throughout the life of the plant, and not only 

 does it appear at the apex of the main branch, but cells of the same kind 

 are found at other points where growth is taking place, e.g., in the young 

 conceptacles and at the point of formation of lateral branches. It seems 

 as if its appearance were the herald of every local development. 



When a new branch is about to be produced, one of the young 

 epidermal cells not far from the apex, and still in the region covered by 

 the apical hairs, develops a markedly mucilaginous wall, and takes on the 

 characters of an apical cell. The cells in its immediate neighbourhood 

 divide in the same way as they do at the primary apex, and cause the 

 thallus to grow out at this point (plate II., fig. 2) ; the filaments which 

 were originally below the thallus branch repeatedly and form a mass of 

 tissue, while the meiistem round the apical cell produces new filaments in 

 the same way as that already described. As the branch increases in size, 

 the basal filaments collect into strands which run at first radially, and then 

 longitudinally, below the cells of the newly formed cortex, and the new 

 branch shows precisely the same structure as the main axis. The apical 

 hairs remain, and are carried upwards by the growing branch. 



THE DEVELOPMENT OF THE CONCEPTACLES. The first indication of 

 the formation of a conceptacle is seen in the alteration of one of the young 

 epidermal cells lying not far from the apical cell. By change in shape and 



* Op. cit. 



