MALE FERN. SPOROPHORE. 195 



others in glycerine. Note the several tissues above 

 observed in the transverse sections : they have in this 

 section a corresponding position relatively to one 

 another : by reason of the frequent splittings and 

 fusions of this bundle-system the several elements will 

 appear contorted and twisted, but this does not materially 

 affect their general arrangement. 



Examine under a high power, and observe 



A. In the Xylem of the bundle 



a. The Scalariform tracheides, which are the 

 main constituents of the xylem : they are elongated 

 prosenchymatous elements, with ladder-like marking 

 of the lateral walls; this is due to the presence of 

 regularly arranged, transversely elongated, bordered 

 pits. Take especial notice of the appearance of 

 the lateral walls as seen in longitudinal section 

 where two tracheides are contiguous with one another ; 

 and compare them with parts of the wall which 

 adjoin. 



I. Cells of the Conjunctive parenchyma inter- 

 spersed among the tracheides. 



c. Tracheides with spiral marking ; these are the 

 first-formed xylem elements, or Protoxylem. 



B. In the Phloem observe 



a. The Sieve-tubes, which are also elongated 

 elements with pointed ends : the surfaces of the walls 

 which separate contiguous sieve-tubes are covered with 

 numerous sieve-plates (best seen in sections treated with 

 Schulze's solution), to which round, highly refractive 

 granules adhere : these stain yellow with Schulze's 

 solution. Note especially the irregular outline of the 

 walls when seen in longitudinal section. 



o 2 



