154 



THE MARATTIALES 



in his earlier studies of this plant failed to find a single initial cell; however, in a 

 more recent paper (farmer 3) he has decided that a single apical cell is present in 

 the young sporophyte of Angiopteris, and he gives figures of this. In longitudinal 

 section (fig. 134) the apical cell appears oblong, with a markedly truncate base, 

 while in transverse section it is imperfectly triangular in outline. I he apical cell 

 of the stem in Kaulfussia (fig. 136, C) is usually somewhat broader than it is in 

 Angiopteris, and closely resembles that of Ophioglossum moluccanum. It has a 

 broadly truncate base and is somewhat narrowed above. In transverse section it 

 approaches the triangular outline of the apical cell in Ophioglossutiu but the seg- 

 mentation is less regular and in this respect it is not unlike that of Angiopteris. The 

 stem apex was examined in three species of Datura, all of which seemed to agree 



Fig. 137. — Kautju 

 A, B. Two transverse sections of a young sporophyte, above C. Transverse section of petiole of cotyledon. Xoo. 

 level of stem apex, show'ng closed sheath formed by D. Vascular bundle of cotyledon, more enlarged, 

 base of cotyledon. I 1 , second leaf. X50. E. Second leaf. 



closely in the form of the apical cell, which is much more definite in Dancea than it 

 is in any of the other genera. Brebner's account and figure of the apical cell in 

 D. simplicifolia agree closely with my own preparations of D. ellipttca, D. jenmam, 

 and D. jamaicensts. 



The apical cell (fig. 140, A), seen in longitudinal section, is very deep and, 

 unlike that of the other genera, is not usually, at least, truncate below, but pointed, 

 so that it closely resembles in form that of Botrychium or llelmmthostachys. In 

 transverse section it also usually appears triangular, so that it is tetrahedral like 

 that of Botrychium. While the segmentation is somewhat less regular than in 

 Botrychium, nevertheless the limits of the younger segments can be followed without 

 much difficulty, especially in longitudinal sections, although the exact sequence of 

 the divisions in the segments themselves did not seem to be absolutely regular. 



In all of the species the tissue derived from the inner cells of the segments of 

 the apical cell, or cut off from the base of the apical cell itself, remains as undif- 

 ferentiated parenchyma and contributes only to the central pith of the stem. Except 



