172 



THE MARATTIALES 



Below the level of the stem apex, the stele of the axis closely resembles that 

 already described from the somewhat younger plant and forms a somewhat irregular 

 crescent, evidently composed of two portions which are joined on the side facing the 

 two leaf traces from the oldest leaf which shows in this section. The opening of the 

 crescent at this level is turned away from the leaf. No permanent elements are 

 present in the central stele as yet. Following this downward, the crescent is seen 

 to open on the side next the two oldest leaf traces and there is thus formed a foliar 

 gap, while on the opposite side the space becomes closed. In section D, which 

 is taken lower down, the position of the section of the central stele is reversed. At 



Fig. 156. 



A-D. Four transverse sections of a young sporophyte of D.jenmani. X20. Section C shows stem apex. 



E. The apical meristem with apical cell of stem, x, and a leaf initial, /. Xi8o. 

 F-I. Four sections from the same series, but taken lower down. X20. Figs. F, G, show fusion of double leaf trace with central 

 stele, m, mucilage ducts. Between the mucilage ducts in G can be seen the small commissural strand. 



this point the section of the central stele forms a crescent of tissue, most of which 

 has not passed beyond the procambial stage. This crescent-shaped mass is evi- 

 dently composed of two parts and represents mainly the basal undivided bundles 

 of the two youngest leaves. Tracheary tissue has begun to develop in the older of 

 these two masses. Occupying the space within this crescentic stele are three young 

 mucilage canals, but none are yet developed in the cortical tissue of the stem. 

 Within this central space there can also be seen the section of a small isolated group 



