74 THE OPHIOGLOSSALES 



begun tn develop; but this second root developed much earlier in its relation to the 

 development of the next leaf than was usually the case. 



In the present plant the root corresponding to the third leaf, which was the 

 third root in this case, was in a very early stage of development and had not begun 

 to elongate at all. The third leaf in median section was already pretty well advanced 

 and the apical portion was very strongly incurved, as it is in the young leaves of" 

 Botrychium virginianum, which it resembles more than it does that of B. lunaria, 

 and it also suggests the form of the young leaves in the Marattiacc.c. I he basal 

 part of the young leaf, however, is exactly like that of B. lunaria. The stipular 

 sheath forms a thick body, projecting forward and about equal in height to half the 

 total length of the young leaf. It is strongly concave below, and the next leaf is 

 fitted into the cavity (fig. 48, (.'). The forward margin extends downward as a sort 

 of lip which elongates rapidly and keeps pace with the growth of the young leaf 

 inclosed within it, and this is completely concealed until it has reached a large size. 

 The sheath finally forms a long, conical protuberance at the base of the leaf to which 

 it belongs. 



The cavity below the sheath is extended backward, so that the base of the leaf 

 is hollowed out in front and in section appears much narrower than the part of the 

 petiole above the insertion of the sheath; this brings the stele of the leaf very close 

 to the epidermis at this point. The narrow cleft thus formed between the posterior 

 wall of the stipular cavity and the petiole of the leaf in front is the "canal," which 

 Gwynne-Vaughn described as occurring at the base of the petiole of the older plant 

 and opening above the insertion of the stipule. These canals are easily seen in longi- 

 tudinal sections of the young bud (tig. 48, B) and it is very clear that they are, in truth, 

 nothing but the narrow spaces between the bases of the adjacent leaves. Clwynne- 

 Vaughn's statement that they open above the insertion of the stipules is incorrect 

 unless the stipules of a given leaf are considered to be derived from the sheath sur- 

 rounding the base of the leaf, this sheath properly belonging to the next older leaf. 

 Ibis canal can be seen as a narrow slit in the young leaf, extending below the inser- 

 tion of the next younger one, the young stele of the leaf being separated from the 

 epidermis at this point by only about three rows of cells. 



I he stele of the young leaf can be traced nearly to its tip, and then continues 

 downward toward the inner side of the leaf into the internode, below where it joins 

 the young stele belonging to the next younger leaf. 



As in the younger sporophyte, the stem apex is of very limited extent and the 

 apical cell shows the same form. In the section figured (fig 48, C) the youngest leaf 

 is cut almost in a median plane and though externally no differentiation is visible the 

 young stele is already conspicuous and can be followed down without difficulty. 

 Passing on one side- of the stem apex and above the leaf trace, there is no evidence of 

 procambium in the apical region of the stem. In the young sporophyte, therefore, it 

 is perfectly certain that no cauline stele is present. Farmer (Farmer 2) states that 

 in the older sporophyte the stele can be traced above the insertion of the youngest 

 leaves, but we believe a careful study of this point in the older plant would show, as 

 in the younger one, that the stele is developed in the young leaf at an exceedingly 

 earh period and that the stele of the internode is composed entirely of leaf and root 

 traces. The procambium tissue developed on the ventral side of the stele near the 

 apex can be shown, by a study of its transverse sections, to be due entirely to tissue 

 derived from the leaf traces, which are extended downward until they meet on the 

 ventral side of the internode. 



Near the stem apex are numerous small scales and hairs filling up the space 

 about it and probably associated with the prevention of drying up of the stem 



