170 PRACTICAL BOTANY. 



stomata) consists of conical cells, with few, very large 

 chlorophyll granules. 



2. Beneath this is the Spongy parenchyma, which 

 encloses 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 otherwise embed- 

 ding them, 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 (cf. 

 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 

 described. Passing towards the apex of the bud observe 

 successively earlier stages of their development. 



Examine the sections with a higher power, and 

 observe : 



