c. 
INTRODUCTION 
and filled with a delicate granular mass. It may also at times be observed that 
this mass is exuded at the last articulation, and surrounds this as a crust. These 
parts are frequently longer than the capsules, and are easily distinguished from 
the young capsules.” The late Professor Don, who wrote the above, adds — “It is 
certainly probable that they are the stamina of Ferns ; and indeed Link found 
them, after frequent search, in most of the Ferns which he submitted to micro- 
scopical examination.” [It is now known that they are merely abortive theca;, 
the hair-like bodies called paraphvses. — A.II.] Mr. Henderson, in an interesting 
paper on ‘ The Germination of Ferns,’* denied that there was any impregnation in 
Ferns, Mosses, or Equiseta; yet, in an after paper read before the Linnean 
Society, on ‘ The Reproductive Organs of Equisetum,’ he states that he had found 
two kinds of granules in the unripe thecae of Ferns, Lycopodium, and Opliio- 
glossum ; that the one kind was mostly absorbed during the maturing of the 
other ; and by submitting each to the test of iodine, he proved the one to he 
amylaceous or starchy, the other more of the nature of pollen. [These specu- 
lations were, however, all wide of the truth ; recent researches have made us 
pretty well acquainted with the mode of reproduction of the Ferns and their 
Allies, and we know that we have not to seek for the representatives of stamens and 
pistils in the sori of the perfect plant, hut upon the structures developed from 
the spores in germination. In following the order of the phases of growth of the 
Ferns, it is best to commence with the fruit of the parent plants. — A.II.] 
Theca and Sorus. The spores in all the species are contained in capsules or 
theca:, each of which opens by a transverse irregular fissure, and is furnished with 
a jointed ring nearly surrounding it (the annulus), by the elasticity of which 
the capsule is torn open and the spores dispersed (see figs, e and f in the 
woodcut illustrative of the genus Grammitis). The thecae are collected into 
linear, oblong, or circular clusters, called sori, of which Professor Link thus 
writes :f — “The sorus is in general situated on a receptacle, which, when 
roundish, consists entirely of short spiral vessels, so called vermicoid bodies, 
similar to the thickened extremities of the leaf-nerves, which might therefore lie 
regarded as abortive receptacles. In the elongated receptacles, spiral vessels are 
also met with.” The sori are in some tribes of the Ferns naked (woodcut of 
Polypodium, figs, b and c),but in the generality covered with a scale or indusium, 
of shape similar to themselves (woodcut of Aspidium, fig. b). 1 remarked in the 
first edition, that the origin of this integument was undoubtedly similar to that of 
the scales, namely, disrupted epidermis. Microscopic observations, however, 
induce me to doubt this assigned origin for the indusia, and to consider them as 
distinct organs, as much so, indeed, as the calyx of a flowering plant, or the 
calyptra of a Moss. Whether they arise from the vermicoid bodies of Link, 
just spoken of, or not, I have been prevented from observing. These certainly 
attend the genus Woodsia, and are intermingled with the thecae, the genus having 
no real indusium. In the genera Cystopteris, of Aspidium, Adiantum, I’teris, 
Map. of Zoology and Uotany. vol. i, p. 340. 
t Ann. of Nat. History, Aug. 11140. 
