THE HIGHER CRYPTOGAMIA. 321 



small spores the starch grains are exceedingly small and 

 exhibit no structure. 



The ripe fruit of PiMaria glohdifera splits into four 

 valves. The sporangia burst by the vast expansion of the 

 internal jelly produced by the dissolution of the special 

 mother-cells ; the jelly becoming distended by the absorp- 

 tion of water. Numbers of large and small spores thus 

 become free. 



A few hours after this process the germination of the 

 large spores commences. The first indication of this is the 

 appearance of a lenticular agglomeration of finely granular 

 protoplasm on the inner side of the apex of the spore, 

 underneath the pyramidal arch formed by the triangular 

 lobes of the inner membrane. This mass of protoplasm is 

 soon clothed with a membrane, and then constitutes a very 

 flat cell with a circular outline (PL XLIII, fig. 2). Shortly 

 afterwards, before the expiration of twenty-four hours, the 

 conical cavity formed by the lobes of the glassy layer of 

 the outer spore-membrane appears to be filled by a cellular 

 body, consisting of a large central cell surrounded by a 

 simple layer consisting of a few tabular cells (PI. XLIII, 

 ligs. 3, 3*, 5). I did not succeed in finding the interme- 

 diate stages between this condition and the one previously 

 described, but I do not doubt that this cellular body is pro- 

 duced by repeated bi-partition of the lenticular cell which is 

 arched above. The lenticular cell may be first divided into 

 four, by the production of septa cutting one another at right 

 angles. It is probably one of these four cells, which- 

 being divided by a diagonal septum inclined inwards gives 

 rise to the formation of the central cell, which latter cell 

 growing more vigorously than the rest, soon occupies the 

 middle point of the cellular body, and is covered by the 

 other four cells which in the mean time have divided by 

 septa perpendicular to the outer surface (PI. XLIII, fig. 3). 

 The central cell afterwards divides into a lower, flat, tabular 

 cell, and an upper, spherical one. The lower tabular cell 

 soon divides by repeated bi-partition into four (PL XLIII, 

 fig. 5), then into eight, and afterwards into twelve cells. In 

 the lower part of the prothallium thus formed, the cells 

 which surround the sides of the larger central cell ultimately 



21 



