ASPIDIUM SPOROPHYTE 303 



little very dilute potash may be added if the sections 

 are not transparent enough, or they may be treated 

 first with " eau de javelle," and then be mounted in 

 glycerine. 



If any one of the sections has passed through the 

 apical cone, in a median plane, the apical cell will be 

 seen presenting a wedge-like appearance, and the cells 

 around it will show, in the regularity of their arrange- 

 ment, that they have been derived from segments 

 successively cut off from the apical cell. (Compare 

 Fig. 14.) It may be concluded from the observation 

 of transverse and median longitudinal sections that 

 the form of the apical cell is that of a three-sided 

 pyramid. 



The structure and mode of origin of the young leaves 

 should also be observed in the median longitudinal 

 sections. 



Similar preparations should also be made from the apex of the 

 rhizome of Pteris : in these a single apical cell may be found, 

 having the form of a two-sided cone (i.e. like half of a biconvex 

 lens). 



Tlic Root. 



XIII. Cut transverse sections of the root of the Male 

 Fern, selecting for that purpose the thickest part of 

 an old root : mount in glycerine, and observe 



1. The piliferous layer : a single layer of superficial 

 cells have grown out as root-hairs, remnants of which 

 may still be seen. 



2. The greater part of the section consists of the 

 bulky, brown-walled cortex, of which the outer parts 



