76 FILICALES. [AcROGENs. 



connected with hybrid action ; and I agree with Link, in his first view of the question 

 that the function of the Antheridia nondum sitperspecta et declarata, an opinion which 

 he has, however, since abandoned in favour of these bodies being anthers. They may 

 be bodies analogous to anthers ; but if so they have none of theu' stinicture. 



NageH has lately mentioned that the spiral threads, with an active motion, ah'eady 

 mentioned under Mosses, also exist in some Ferns. He found them abundantly in the 

 germinating leaf of Aspidium augescens, and elsewhere, traced their development, and 

 determined that they are produced among the earliest cells that go to the composition 

 of a fern-leaf. (See Schleiden and N'dgeli, Zeitschriftfiir Wissensch. Bot. s. 1. 168. t. 4.) 

 The stems of Ferns, when arboi'escent, are objects of great interest to the botanist, 

 partly on account of their rarity, secondly, because of their singular structvire, and 

 especially because they offer the highest form of development in Flowerless Plants. 

 It has not been till lately that they have been well miderstood ; they have now, however, 

 received full illustration from Mohl, in Martius's beautiful Icones Plantarum Crypto- 

 gamicarum. One of the most interesting of them is that of the Baranetz or Barometz, 

 called also the Scythian Lamb, in which, by cutting off" the leaves, except a small portion 

 of the stalk, of a woolly- stemmed species, and tm^ning it upside-down, simple people 

 have been persuaded that there existed in the deserts of Scythia creatm'es half animal 

 half plant. 



The veins of the leaves of Ferns have been sometimes described as dichotomous ; it is 

 only, however, in a certain number that this pecuUarity occurs. In some they are 

 simple, in others they are collected in lozenge shaped meshes, and m some they are 

 still differently arranged. Langsdorf and Fischer seem to have been the first to pay 

 attention to these peculiarities, which have been admirably applied to the characters of 

 genera by Adolphe Brongniart and Preel, who have shown them to be of the first 

 importance in distinguishing genera. 



Bory de St. Vincent elevates Ferns to the rank of a class, intermediate between 

 Monocotyledons and Acotyledons ; but at the same time he attaches no importance to 

 the descriptions of those writers who, having seen the germination of the sporules, have 

 attempted to prove an identity between them and Monocotyledons in that respect. He 

 justly observes, that the u-regular unilateral scale which has been seen to sprout forth 

 upon the first commencement of their growth is extremely different from the cotyledon 

 of Monocotyledons, which pre-exists in the seed and never quits it, but swells durmg 

 germination, and acts as a reservoir of nutriment for the young plantlet. He most 

 properly regards it as an imperfectly developed primordial leaf. 



In some modern books of Botany Ferns are broken up into several distinct 

 natural orders, which in my opinion are not to be maintained. But it does appear 

 that three essentially distmct groups exist among them. Of these the largest portion 

 consists of what were once named " dorsiferous ferns," m all which the spore-case is 

 furnished with an elastic rmg or band ; in tAvo other groups, of inconsiderable extent, 

 the spore-cases have no such band. In one of them the cases are often immersed in 

 the tissue of the back of the leaf, and partially, or entu-ely, united by their touching 

 edges into many-celled bodies ; in the other, the spore-cases appear to be nothing more 

 than an alteration of the edge of a contracted leaf. Hence arise the tlu'ee following 

 orders : — 



ISatural Orders of Filicals. 



Spore-cases ringless, distmct, 2-valved, formed on the marqin of a'\ ^n r^ 

 contracted leaf ! . . . . . . . 1 23. OpHioGLossACEiE. 



Spore-cases ringed, dorsal or marginal, distinct, splitting irre-\c, p 

 gularly \ ' ^olypodiace^. 



Spore-cases ringless, dorsal, connate, splitting irregidarly 63/ a "I ok rk 

 ventral cleft / ^^- ■L'an^ace^. 



