158 CEYPTOGAMOUS OR FLOWERLESS PLANTS. [SECTION 17. 



minate upward in a leaf-stalk. The subterranean trunk or stem of any 

 strong-growing herbaceous Fern shows a similar structure. Most Ferns 

 are circinate in the bud ; that is, are rolled up in the manner shown in Fig. 

 197. Uncoiling as they grow, they have some likeness to a crosier. 



487. The fractification of Ferns is borne on the back or under side of 

 the leaves. The early botanists thought this such a peculiarity that they 



606 507 502 



always called a Fern-leaf a Feond, and its petiole a Stipe. Usage con- 

 tinues these terms, although they are superfluous. The fruit of Ferns 

 consists of Spoke-cases, technically Sporangia, which grow out of the 

 veins of the leaf. Sometimes these are distributed over the whole lower 



Fig. 501. The Walkiug-Fem, Camptosorus, reduced in size, showing its fruit- 

 dots on the veins approximated in pairs. 502. A small piece (pinnule) of a 

 Shield-Fern : a row of fruit-dots on each side of the midrib, each covered by its 

 kidney-shaped indusium. 503. A spore-case from the latter, just bursting by the 

 partial straightening of the incomplete ring; well magnified. 504. Three of the 

 spores of 609, more magnified. 505. Schizsea pusilla, a very small and simple- 

 leaved Fern, drawn nearly of natural size. 506. One of the lobes of its fruit- 

 bearing portion, magnified, bearing two rows of spore-cases. 507. Spore-case of 

 the latter, detached, opening lengthwise. 508. Adder-tongue, Ophioglossum: 

 spore-cases in a kind of spike: u, a portion of the fruiting part, about natural 

 size; showing twp r0W8 pf the firm spore-cases, which open transversely into two 



