26 PROCEEDINGS OF SOCIETIES. 



appeared to be merely a sub-variety — i.e. a monstrous form of only accidental 

 annual occurrence. 



Since ray return, however, happening, after a lapse of nearly two years, to be in 

 the neighbourhood of the station where I first found the original three plants, I 

 visited it, to see how the station was getting on ; when, to my surprise, I found no 

 less than eight plants, all partaking more or less of this character, three of these 

 exactly identical with my former specimens, as you may see on comparing the 

 plants on the table with these dried fronds. Four of the plants then found exhi- 

 bited the digitate form in full perfection ; the others, all more or less per- 

 fect ; one, in addition to the conversion of its lower pinnules in a pinnate pinna, 

 having some of these pinnule3 again converted into spore-bearing sprays, showing 

 in a beautiful manner the structure and development of that organ : two of these 

 have been figured (plate 5), the plant to the left representing the most perfect of 

 my specimens obtained in 1854 ; that on the right, another of the specimens then 

 obtained, illustrating in a remarkable manner the way in which the deltoid form 

 is produced. 



From examination and comparison of these forms with other modifications of 

 this fern, it may be easily seen that, as conjectured by me on a former occasion 

 (vide ante Proc. Sec, p. 5.5), the fruitful part of the frond of Botrychium is to be 

 looked on rather as being the analogue to a branch, than a leaf ; being a branch 

 whose pinnules, representing the leaves, have been modified into spore cases, repre- 

 senting the flowers placed sessile around the branches. One of the specimens on 

 the table well illustrates this passage ; first, we have the ordinary barren branch 

 taking on the deltoid type, and then one of the so-formed triangular pinnse having 

 some of its minor pinna? converted into spore cases ; and on dissecting this plant I 

 found that the young fronds, which are to be found folded up at the base of the 

 plant, all exhibited the same curious type, so that, for three generations at least, had 

 this plant been undisturbed, these same anomalous characters would have been 

 preserved. I may add, that dissections of other specimens of the variety gave the 

 same results. This constancy of its characters, through succeeding years, places 

 the plant among my varieties. 



The next question is, to what variety should it be referred ; and even a cursory 

 examination shows, that though so seemingly different in appearance, it really 

 belongs to the g^roup with cristate apices to the fronds, and for which I proposed 

 the name of Cnstatum ; for, on comparison with the forms of the common harts- 

 tongue (Phyllitis Scolopendrium) referable to that group, especially the highly 

 compound form called by its discoverer Digitatum (vide Nat. Hist. Rev., vol. 1, 

 page 145; note), we find that exactly parallel changes take place, the veins 

 which should normally be aggregated in a single bundle becoming separated into 

 several bundles and thus branched, the outline of the simple linear frond thus 

 becoming partially branched, even as in this case the simple linear outline of the 

 partite frond has become deltoid, of course the venations being of different types 

 in the two plants, this distinctive type is also kept up in the varieties. 



In Botrychium lunaria var. cristatum, the following changes take place. In 

 the ordinary form two distinct classes of venation are observable in the barren and 

 fertile branches respectively. "We find, commencing at the ground, that we can 

 trace four distinct sets of vessels running up the stem, two destined for the fruit- 

 ful, and two for the barren branches. Those in the barren branch again pass up 

 as two distinct sets, one on each side of the axis, each set giving off" a single bundle 

 of vessels to each pinnule of its own side ; and the two finally giving origin to a 

 number of veins, arranged as a fanshaped venation at the apex of the frond. The 

 bundle of fibres given otF to each pinnule, in its turn giving origin to veins fan- 

 shaped in their arrangement, each pinntde, indeed, exactly analogous to the apex 

 of the frond. 



In the fruitful branch we find each bundle giving off two bundles to each of its 

 bunches, these bundles in their turn giving rise to either double or single bundles, 

 according as the branch which they supply is branched or not — in short, each 

 terminal bunch or cluster representing the single pinnule of the barren branch. 



