46 



111 I OPHIOGLOSSALES 



in the mid-region of the sporoph) te ( fig. i~, C), the only difference noted is a slightly 

 greater development of the xylem. I In- section of the root (fig. 27, D) presents 

 almost exactly the same appearance as that of the leaf. Whether we should call the 

 root bundle "monarch" or "collateral" is merely a question of terms. In the mid- 

 region the endodermis can he clearly seen, and it is then evident that the xvlem is 

 separated from it by a single layer of pericycle cells. 



Fig. 28. 



A. Archcgonium of Botrychium virginianum, containing a two-celled embryo. X275. 



B. Four longitudinal sections of an embryo with 7 cells. X275. 



THE EMBRYO OF BOTRYCHIUM. 



The following account of the development of the embryo of Botrychium is 

 based mainly upon material of B. virginianum furnished me through the kindness 

 of Professor Jeffrey. 



In this species, as in the other Eusporangiatae, there is a marked increase in the 

 size of the fertilized ovum before the first division takes place. At the time of the 



Fig. 29. -Young embryo ' B ryehium virginianum. 

 Longitudinal sections. X200. b b, basal wall. A. Four-celled embryo. H 1). Oldei stages. 



hist division the ovum is generally more or less elongated, bur this is not always the 

 case. I his elongation is less marked in B. lunaria (rig. 36), while in B. obliquum 

 the ovum becomes much elongated before the first division occurs (see Bower 9, 

 fig. 266). 



