SELAGINELLA SPOROPHYTE 269 



conical cells, each of which contains a single large 

 chlorophyll corpuscle, which is usually closely 

 applied to the internal wall of the cell: in sections 

 suitably stained it may be seen that the nucleus of the 

 cell is closely applied to the large chloroplast. Stornata 

 are absent. 



2. Beneath this is the spongy parenchyma, which 

 incloses centrally 



3. A single vascular bundle. 



4. The epidermis of the lower surface consists of 

 smaller cells containing chlorophyll, and with stomata, 

 opposite the midrib : note the two small guard-cells as 

 seen in transverse section. Near the margin of the leaf 

 the upper and lower epidermal layers are in contact 

 with one another, the spongy parenchyma being there 

 absent. There is also a marginal band of thickened cells. 



IX. Choose out from material which has been 

 hardened in alcohol the apical buds of branches 

 which have not as yet begun to form sporangia : 

 holding these between pieces of pith or carrot, or, 

 better, embedding them in paraffin, cut longitudinal 

 sections : mount them in glycerine, examine first with 

 a low power, and select those sections which are 

 nearest to the median plane, i.e. those which show the 

 greatest regularity of parts, and the stem terminated 

 by the apical cone. 



In such sections observe 



1. The axis, with tissues as above described in the 

 longitudinal sections, and terminated by the apical 

 cone : borne laterally on this are 



2. The leaves, each having a ligule attached to 

 its upper surface : note also their structure as above 





