152 



THE MARATTIALKS 



ably present in the phloem, but in material mounted in Canada balsam the sieve 

 tubes are very poorly differentiated. 



Upon the cotyledon as well as upon the later leaves in Daneea very character- 

 istic peltate scales are developed. These arise as single club-shaped cells, tin- 

 swollen end of which is cut off by a cross wall. In the uppei cell, which broadens 

 rapidly, a series of vertical walls arises, sometimes arranged very regularly (rig. 

 129, E). In the cast- figured there had evidently been two median, intersecting walls, 

 so that the cells were arranged in a somewhat quadrant fashion; more commonly 

 the divisions are less regular and the cells increase considerably in size by 

 further divisions. A section of an older scale may be seen in fig. 131, C. Stomata 

 are developed upon the lower surface of the cotyledon in all of the Marattiaceae. 

 These have already been referred to in the case of Marattia, and in Angiopteris 

 they are very similar to those found in Marattia. In Daneea, previous to the 

 formation of the stoma, there are several preliminary divisions, the cells being cut 



!(.. I33 



Three longitudinal sections of a young iporopbyte of M aratt ia dou 

 cut in the plane of the cotyledon, cot. rf, stem apex; r,motape\. 



li... 134. 



I - ■ . nearl} median sections of a young sporophyte of 

 Angiopteris. cot, cotyledon; si. stem apex. I', 

 second leaf. <75- The bundles of the cotyledon 

 and primary root are continuous. 



off in a spiral fashion, the last division resulting in the formation <>f the mother cell 

 of the stoma (tig. 12c;, C.). The complete stoma appears, then-ton-, surrounded by 

 a series of somewhat concentrically arranged accessory cells (tig. 1 20, /)). Similar 

 accessory cells, but much less developed, can be recognized in Marattia also. 



The stomata of Kaulfitssiti have long been known for their gnat size and the 

 fact that they form permanently open pores, a peculiarity aheadv developed in the 

 stomata of the cotyledon. These are very much larger than those of the other genera 

 and can be readily recognized by the naked eye as little dots. I he guard cells 

 become very large (tig. 128) and strongly curved, so that the stoma appears almost 

 circular in outline, with a very large permanently open central pore. I his hum 

 pon is surrounded In concentrically arranged series of cells, suggesting that the 

 mother cell of the stoma is cut off very much as in Daneea, but material was want- 

 mi; tni a thorough investigation of this point. 



