The Retention of Vitality of Moss Protonema. 139 
but in the older parts of the filament they become very much crowded 
together and somewhat irregular in shape, and are elongated in the 
direction of the long axis of the cell (Fig. 1, B). 
F 10 . 1. Moss protonema produced in culture of Barnfield soil 1870. A, 
apical cells ; B, middle cells ; C, basal cells of filament, a, colourless attaching 
cell, x 428 diameters. 
