XI 



LEPTOSPORANGIAT^ HETEROSPOREM 



419 



about 20° C, within about an hour after the spores are placed 

 in water. Previous to this the nucleus enlarges and moves to 

 one side of the spore, usually the point opposite the apex, and 

 the granular cytoplasm collects near the centre and is connected 

 with the peripheral cytoplasmic zone only by thin strands. 

 The first wall divides the spore into two very unequal cells, the 



Fig. 244. — Marsilia vestita. Germination of the microspores, X450; x, vegetative pro- 

 thallial cell; m, basal antheridial cell; p, peripheral antheridial cells; A, an unger- 

 minated spore, ventral aspect; B, section of a similar one — all longitudinal sections 

 except E and F, which are transverse. In these the two groups of sperm cells are 

 separated by a large sterile cell. 



smaller containing but little granular contents, and representing 

 the vegetative part of the prothallium, while the upper becomes 

 the antheridium. In Pilularia there is subsequently cut off a 

 small cell from the vegetative cell, and BelajefT (4) states that 

 this also is always the case in Marsilia, but it is less conspicuous 



