loS CKYPTOGAMOUa OU FLOWEllLESS PLANTS. [SECTION 17. 



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

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

 are cireinatc in the bud ; that is, are rolled up in the manner shown in Tig. 

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



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

 the leave- The early botanists thought this such a peculiarity that they 

 606 507 502 



always called a Fern-leaf a Frond, and its petiole a Stipk. Usage con- 

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

 consists of Spore-casks, technically Sporangia, which grow out of the 

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



Fig. 501. Tlie Wulkiiig-Fern, Camptosorus, reduced in size, showing its fruit- 

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

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

 kidney-shaped indusinin. 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 509, more magnified. 605. Schizoea pnsilla, a very small and simple- 

 leaved Fern, drawn neai:ly of natural size. 506. One of the lobes of its fruit- 

 beariv/g 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: ri, a portion of the fruiting part, about natural 

 size; showing two rows of the firm spore-cases, which open transversely into two 

 valves 



