2;88 



FOUNDATIONS OP BOTANY 



Fia. 210.— Spore-Plamt of a Tern (Aspidium MUx-mas). 

 ^, part of rootstock and fronds, not quite one-sixth natural size ; fr, yoting fronds 

 unrolling ; JB, under side of a pinnule, showing sori, s ; C, section through a 

 sorus at right angles to surface of leaf, showing indusium, i, and sporangia, 8 ; 

 I>, a sporangium discharging spores. (£ is not far from natural size. C and 

 D are considerably magnified.) 



