54 PHARMACEUTICAL BOTANY 
Fic. 28.—Dryopteris (Aspidium) Filix-mas. % nat. size. A, Sorus and portion 
of pinnule bearing same, in cross section, X 20. (After Kny.) B, Pinnule with 
young sori, each covered with an indusium. C, the same, showing a later stage 
of the sori, with shrivelled indusia.* Both slightly enlarged. (From Strasburger, 
Noll, Schenck and Schimpers Lehrbuch der Botanik.) 
