FIG. 271. A fern (Aspidium Filix-mas) 



A, part of the creeping stem, or rootstock, and fronds: fr, young fronds unrolling. 

 B, under side of a frond, showing sori s. C, section through a sorus at right 

 angles to surface of the leaf, showing indusiura i and sporangia s. D, a spo- 

 rangium discharging spores. After Wossidlo 



