1 66 Shiv Ram Kashyap. — The Structure and Development of 
be so formed that a cell-mass results (Figs. 5, 7, 9). After the formation of 
these cell-walls, cells from the surface may project upwards by increase in 
length (Figs. 5, 6 ) and ultimately by further divisions develop into the 
characteristic lobes ; or only a single cell projects outwards from the cell- 
mass, and this in its turn gives rise to several cells which project upwards 
and form the characteristic lobes (Fig. 7). Thus when a cell-mass is first 
formed after the germination of the spore the prothallus body may be 
formed directly or indirectly through the formation of a ‘primary tubercle’. 
In the meantime rhizoids grow out from the lower surface which fix the 
erect prothallus to the soil (Figs. 14, 15). 
Mature Prothallus. 
As described above, the lobes arise from single cells which have in- 
creased in length and project above the general level, and are naturally 
