330 THE EMBRYO OF SELAGINELLACEAE 



and divides into two cells by a transverse wall. The outer of 

 the two daughter cells takes no part in the formation of the 

 sporophyte, though elongating and often dividing several times 

 These cells are termed the suspensor (Fig. 240, s) and function 

 in pushing the lower daughter cell down into the nourishing tis- 

 sue of the gametophyte. The lower daughter cell, by a series 

 of divisions that at first resemble the common ferns, forms the 

 young sporophyte. This consists of a stem with one or two 

 cotyledons, a massive foot and finally, at a late period in the 

 development of the sporophyte, of a root (Fig. 240). The tardy 



Fig. 240. Gametophyte of Lycopodium as seen in section: an, anthcridia; 

 ar, archegonia. The young sporophyte or embryo developed in one of the 

 archegonia consists of a foot, /; a root, r; and a stem, st, bearing a leaf on 

 either side; s, the suspensor, which has pushed the sporophyte early in its 

 development into the tissues of the gametophyte. Above a single male 

 gamete is figured. — After Bruchmann. 



development of the root has been cited as an indication of the 

 origin of the lycopods from very primitive ancestors, in which 

 the formation of the root had not become established. It may 

 also be due to the abundant food stored in the gametophyte and 

 hence the development of the root might well be delayed until 

 this store is exhausetd. The growth of the sporophyte is very 

 slow and it remains as a parasite upon the gametophyte for a 

 long time, even for years in some of the subterranean forms 

 (see Ophioglossales). The elongation of the stem and root is 

 effected by the division of several cells rather than by one apical 



