XIII 



LYCOrODINEJE 



531 



The whole closely resembles Goebel's figures of 6^. spinosa. A 

 comparison with older stages indicates that from this central 

 cell alone the sporogenous cells are produced, as in Lycopodium 

 selago. The outer row of cells does not divide by periclinal 

 walls, and from the first forms an extremely distinct layer. 

 The first cell cut off from the archesporium divides again by a 

 periclinal wall (Fig. 307, B), and the inner cell forms prob- 

 ably the first tapetal cell, although in some cases it looks as if 

 this cell took part in the formation of spores. The arche- 



FiG. 308. — Selaginella Kraussiana. A, Radial section of a nearly ripe microsporangium, 

 Xioo; /, ligula of the subtending leaf; t, itapetum; B, section of young macro- 

 sporangium (about half grown), showing the papillate tapetal cells it), X6oo; C, 

 section of the wall of a young macrospore from the same sporangium, X6oo. 



sporium undergoes repeated divisions to form the sporogenous 

 tissue, and finally the layer of cells between this and the pri- 

 mary wall divides by periclinal w^alls to form the tapetum, 

 which here remains intact until the spores are nearly or quite 

 mature. The formation of the stalk is the same as in Lyco- 

 podium. 



It is quite possible that the apparently single archesporial 

 cell of wS'. Kraussiana may be one of a transverse row of arche- 

 sporial cells, like those of 5'. Martensii. 



