32 



SCIENTIFIC AND APPLIED PHARMACOGNOSY 



Powder. Light brown or light greenish-brown (Fig. 14); starch 

 grains numerous, ellipsoidal, ovoid, oblong and irregularly shaped, 

 varying in length from 0.002 to 0.018 mm.; numerous oil globules 

 seen in chloral mounts; tracheae long and with scalariform and reticu- 

 late thickenings, the cells being 0.025 to 0.075 mm. in width. The 

 tracheae are colored reddish-violet on the addition of concentrated 

 sulphuric acid, the reaction resembling that of lignified cells with 

 phloroglucin; few reddish-brown epidermal cells are present, and 

 the strongly lignified cells of the hypodermis resemble the libriform 



FIG. 13. Transverse section of stipe of Dryopteris marginalis, showing epidermis 

 (E), hypodermis (H), endodermis (N), completely surrounding the vascular 

 bundle (V), and which consists of sieve (S), tracheae (T). 



cells in higher plants. Many of the cells of the parenchyma contain 

 nuclei which may be differentiated by the use of iodin green or 

 methyl green. 



Constituents. An active, amorphous substance, filicic acid, 

 2 to 8 per cent, being contained apparently in greatest abundance in 

 rhizomes collected in autumn, and readily decomposing with the 

 formation of an inactive but crystalline anyhdride; and filicic anhy- 

 dride (filicin, or so-called crystalline filicic acid). The latter occurs 



