LYCOPODIUM. SPOROPHORE. 177 



band of lignified tissue (brown with Schulze's solution). 

 Here and there may be found in the cortex small 

 groups of very narrow elements, having a dark appear- 

 ance : these are single Vascular bundles of the 

 leaf-trace, cut through on their course from the 

 leaves to the central vascular cylinder. A sudden 

 transition is found from the inner sclerenchymatous 

 band (c) of the cortex to 



3. The tissue, which lies next to it internally. This 

 tissue consists of two to three layers of tangentially 

 elongated cells, the walls of which have a sharp con- 

 tour, are not thick, and stain with Schulze's solution 

 a slightly different tint of brown from the walls of 

 the sclerenchyma : this band is regarded as taking the 

 place of the Bundle-sheath, which is met with in 

 most of the Pteridophyta as a definite layer of cells. 



Treat a section with sulphuric acid : the walls of this band 

 will be found to resist* its action more than the rest of the tissues, 

 the walls being of a corky nature. Note also that the cuticle is 

 brought into greater prominence by treatment with sulphuric 

 acid, since it resists the action more strongly than the other 

 walls. 



Within this so-called bundle-sheath is found 



4. A cylindrical mass of vascular tissue. It is 

 composed, as in other cases, of (a) Phloem tissues, 

 and (&) Xylem tissues, which may be distinguished 

 by their optical properties, and by their staining 

 with various reagents. Observe that the phloem 

 forms a matrix, as it were, in which are embedded 

 the masses of xylem ; the latter are of elliptical form 

 as seen in the transverse section : several of these 



N 



