xiv] 



LYCOPODIUM 



49 



outer tissue of the sporophylls (a). A transverse section in the 

 plane BB of fig. 127 is shown in fig. 129 : the pedicels and a 

 part of each vascular strand are seen at b radiating from the 

 axis of the cone ; one sporophyll (sp, a) is cut through in the 



.1^^ 



^:::^ 



Fig. 129. Transverse section of the cone of Lycopodium cernuum in the plane 

 BB of fig. 127. (After Lang.)] 



region of the pad of tracheal tissue that characterises the short 

 sporangial stalks. The upper portions of the sporangia of the 

 next lower whorl, which project upwards against the mucilagi- 

 nous bases of the sporophylls above (cf. fig. 127, BB) are shown 

 at c and external to them, at a, the section has cut through 

 the outer persistent portions of these sporophyll bases. 



As Lang points out, this highly complex structure is an 

 expression of the complete protection afforded to the sporangia 

 of a plant met with in exposed situations in the tropics ; it 

 is also of importance from a morphological standpoint as ex- 

 hibiting an agreement with the extinct type of Lycopod cone 

 represented by Spencerites. 



Selaginellaceae. 



Selaginella differs from Lycopodium in the production of 

 two kinds of spores, megaspores and microspores, and, in the 



