MICROSCOPIC OBJECTS. 



Fig. 11. Oblique Section of the Root of the Brake Fern 

 (Pteris aquilina), x 90, Acrogen. 



This section shows the scalariform tissue in situ. As will 

 be perceived, it is seated in a mass of cellular tissue, of which 

 the section is chiefly composed. Around the scalariform 

 ducts there is an evident aggregation of smaller cells (see 

 fig. 12 for a further description). 



It is best viewed in the dry state or in balsam. 



Fig. 12. Scalariform Tissue from Brake Fern (Pteris 

 aquilina), x 220. 



Scalariform tissue is found in close bundles ; and imme- 

 diately around these bundles are packed a quantity of wood- 

 cells (see fig. 11). These are again closely packed in paren- 

 chyma or cellular tissue. The name of the tissue is derived 

 from the Latin scala, a ladder, which the ducts greatly 

 resemble. It is chiefly found in the Ferns ; but when met 

 with in the higher plants, it has a tendency to pass into the 

 form of pitted ducts. Scalariform tissue may sometimes be 

 slightly unrolled. 



It shows best when mounted in liquid. 



