PTERIS AQUILINA. 115 



foot absorbs from the gametophyte the nourishment 

 for the embryo sporophyte, but each soon becomes 

 able to provide for itself. 



The gametophyte is not so large or complex a structure 

 as that of the Bryophytes. It is dorsiventral and in 

 several ways greatly resembles the gametophyte of 

 Anthoceros. In the way in which it develops it also 

 shows striking resemblance to Bryophyte gametophytes. 

 The antheridia, which are usually formed on the basal part 

 of the gametophyte, are outgrowths from surface cells, 

 and are not so complex as were those found in Bryo- 

 phytes. The sperms are spiral, bear many cilia, and move 

 with great rapidity. The archegonia have their venters 

 deeply embedded within the gametophyte, but their 

 necks protrude and are so directed that when the tips 

 open they are favorably placed to admit the sperms. 



The first division of the oospore is effected by means 

 of a wall that runs at right angles to the surface of the 

 gametophyte and almost parallel with the long axis of 

 the archegonium. The next wall runs at right angles 

 to the first, and the two divide the oospore into four 

 quadrants, an outer and inner anterior, and an outer 

 and inner posterior. The outer anterior produces the 

 first leaf; the inner anterior produces the first stem; 

 the primary root is produced by the outer posterior, and 

 the inner posterior produces the foot. The embryonic 

 foot and embryonic root disappear, the real stem becom- 

 ing the rhizome from which the secondary roots arise. 

 The primary leaf is also transient, new and larger leaves 

 being formed annually from the rhizome. It is evident 

 that this definiteness in the origin of organs from the 



