SPORANGIA OF FERNS. 



355 



the scissors a narrow strip out of the leaf, parallel with the sorus, 

 clamp this strip between pieces of elder-pith (or pack several 

 such strips together, one behind the other, in which case no elder- 

 pith is needed), and take delicate cross-sections through them. 

 The cross-section (Fig. 130, A) shows us an epidermis* on the 

 upper and under side, and a spongy parenchyma, the cells of 

 which lie more densely together under the upper epidermis. The 



FIG. 130. Scolopendrium vulgare. A, cross-section through the fertile part of the 

 leaf; i, indusium ; sg, sporangium, under each group of sporangia is seen the section 

 of the stele. B-E, sporangia ; B and E, seen from the flanks ; />, from the dorsal side ; 

 C, from the ventral side ; F, a spore. (A, x 50 ; B-E, x 145 ; F, x 540). 



apparently simple linear sorus now appears divided into two* 

 These stand right and left, inclined to one another, each in the 

 angle between the leaf -surf ace and an indusium, and each close 

 over a small stele. The surface of the leaf is here hollowed into 

 a, furrow, and between the two sori rises into a ridge. The epi- 



