177 



but his figm-i;s indicate this, and in the adnlt sporophyte of 

 (>. pendahim the writer has described and figured such a cell 

 (Mosses and Ferns, 2d edit., Fig. 134). 



The shoot apex lies in a narrow depression Ijetween the 

 base of the leaf and a narrow ridge which extends around it 

 on the side opposite the leaf base. This latter structure is the 

 beginning of the conical sheath characteristic of the shoot apex 

 of the older sporophyte. In the only transverse section of the 

 young shoot apex that was obtained the apical cell was trian- 

 gular, as in the other species that have been examined 

 (Fig. 148,t"). 



The leaf forms a conical body with a definite apical cell of 

 tetrahedral form. The apex of the first leaf and stem of the 

 bud are formed quite independently of each other, and in the 

 older stages, when the young vascular bundles belonging to 

 each are developed, they very often are entirely distinct, con- 

 necting with the vascular bundle of the root from which the 

 bud arises at points some distance apart (Fig. 149). Indeed 

 this is sometimes so marked that there is an appearance of 

 two distinct buds side by side, one of which forms the leaf 

 and the other the stem rudiment. 



The leaf rapidly elongates and soon breaks through the 

 overlying root tissues (Fig. 145). A longitudinal section of a 

 bud at this jieriod shows the stem apex at the bottom of a 

 cup-shaped depression, with the apical cell conspicuous, as well 

 as its youngest segments. The beginning of the vascular strands 

 of leaf and stem can be seen starting from tracheids which 

 are now visible in the vascular cylinder of the root from 

 which the bud is developed. 



The first root of the bud itself does not appear until a later 

 period, and it is formed within the stem rudiment. Possibly 

 as in other cases, the apical cell of the root is derived from 

 an endodermal cell of the stem bundle. In the earliest stage 

 that was encountered, however, the root was already established, 

 and its exact origin could not be determined. There is socm 

 evident a central strand connecting wirh the young vascular 



