MARATTIALES 



293 



between. In each half there are differentiated the separate 

 archesporial groups of cells corresponding to the separate 

 chambers found in the complete synangium." The whole 

 process takes, according to his account, about six months. 

 Luerssen was unable either in Marattia or Angiopteris to trace 

 back the archesporium to a single cell, which Goebel (3) claims 

 is present in the latter. 



In Angiopteris the process begins as in Marattia^ but at a 

 period when the leaf is almost completely developed and 



Fig. 164. — Angiopteris cvecta. Development of the sporangium. A, Vertical section 

 of very young receptacle; B, similar section of an older sporangium in which the 

 archesporium is already developed (after Goebel) ; C, longitudinal section of an 

 almost fully-developed sporangium, showing the persistent tapetal cells (0 ; f, the 

 annulus, X75. 



unfolded. The first indication of the young sorus is the 

 formation of an oblong depression above a young vein, and 

 about the border of this are numerous short hairs, which as a 

 rule are absent from the epidermis of the leaf (Fig. 164, A). 

 The placenta is formed as in Marattia, but instead of the two 

 parallel ridges that are found in the latter, the young sporangia 

 arise separately, much as in Botrychium. As in the latter too, 

 Goebel states that the archesporium can be traced to a single 



