QC } BRYACE^E. [Acrogens. 



peristomfuni often alternate with those of the outer, thus conforming to the law of 

 alternation prevalent in the floral leaves of flowering plants ; and, finally, if we compare 

 the virions Btates of the leaves of Buxbaumia aphylla with the teeth of other Um- 

 mosses, it is impossible not to be struck with the great similarity in the anatomical 

 Structure of the two. These considerations led me to the conclusion, that the calyptra, 

 operculum, and teeth of Urnmosses, are all modified leaves ; and hence that the spore- 

 case is to Jt>e considered more analogous to a flower than to a seed-vessel. With regard 

 to ili membrane, or epiphragma, which occasionally closes up the orifice of the spore- 

 cue, it may be considered as formed by the absolute cohesion of the leaves of the peri- 

 Btome just as the operculum of the genus Eudesmia is formed by the cohesion of petals ; 

 and this is confirmed, first, by Calymperes, hi which the membrane ultimately separates 

 into teeth, and by the fact that the horizontal membrane exists most perfectly in such 

 genera a^ 1',,' vtriclium and Lyellia, in which there is no distinct peristome. As to the 

 internal structure of this curious apparatus we may regard the spore-case as the hollow 

 apex of the axis, the Bporules as a partial dissolution of its cellular tissue, and the 

 columella as the unconverted centre. That the end of the axis or growing point of plants 

 frequently becomes much more thickened than the spore-ease of Urnmosses, requires 

 no illustration for those who are acquainted with Eschscholtzia, Rosa, or Calycanthus. 

 That tissue is frequently disintegrated for particular purposes, is proved by the produc- 

 tion of pollen out of the cellular tissue of an anther, and by the general law of propaga- 

 tion that seems to prevail in all the lower alliances of plants ; the same phenomenon 

 may be therefore expected in Urnmosses. That the columella should be left in this 

 dissolution of the tissue might be expected, from its being a continuation of the seta or 

 axis of development, the tissue of which is more compact, and of course less liable to 

 separation, than the looser tissue that surrounds it ; this is analogous to the separation 

 of the pollen from the connective of most plants, or from parts only of the anther of all 

 th,, si genera which, like 7iscum, JEgiceras, or Rafflesia, have what are called cellular 

 anthers. 



.Mr. !",. Quekett has lately proved the general accuracy of these views by the discovery 

 of a monstrous moss, in which common leaves take the place of the spore-case, its peristome, 

 and other apparatus. As this is a very curious subject, I extract at length his observa- 

 tions, with a few unimportant omissions : — " Soon after Mr. Ward made known his plan 

 of growing plants in closely-glazed cases I had constructed a small case, in which were 

 placed various Mosses, both in fruit, and having the tendency to form fruit. Among 

 the number was a mass of Tortula fallax, showing, at the time, the early condition of 

 the seta, capped with a calyptra. After watching the progress of the plants, it was dis- 

 covered that the Tortula, which, when placed in it, showed every tendency to produce 

 fruit, now presented, instead of fruit advancing to maturity, a miniature forest of 

 elevated steins, leafy above and below, but in the intermediate portion, destitute of 

 leaves ; in fact, all appearance of capsules approaching maturity was dissipated. On 

 placing some of the plants under the microscope, it was evident that the specimens were, 

 furnished with the usual leaves at the base of the plant, — the seta existed, and presented 

 the usual brown colour, quite destitute of leaves, but in the place of the capsule, there 

 was a continued elongation of the seta, of a green colour, bearing several green ieaves, 

 n arj ing in number in different specimens, being generally from about twelve to twenty. 

 It appears that the capsule had scarcely commenced to be formed, when the elements 

 of the modified leaves, (which I conceive would have otherwise formed the capsule and 

 peristome), having received an increased degree of heat, combined with more moisture 

 than is natural to these plants, occasioned by the structure of the case, and by its posi- 

 tion, instead of being converted into the ordinary capsule and peristome, the matters 

 which entered the plants were not appropriated to the development of organs of repro- 

 duction, but underwent a change into a state fitting them apparently for the purposes 

 of nutrition." 



Mr. Quekett objects, however, to that part of the theory which assumes the spore-case 

 to be the hollowed apex of the axis ; he considers the theca and operculum to be the 

 representatives of a consolidated calyx ; the corolla to be the lining membrane, whose 

 fringed edge constitutes a peristome, which is cither single or double, and appears to be 

 the representative of the reproductive apparatus ; and the columella to be the recep- 

 tacle, turns or axis on which these several organs are arranged. 



Fine illustrations of the Anatomy of Urnmosses will be found in Link's Ausgcw. 

 . Bot. Abbild. Fate. 1. 



Urnmosses are found in all parts of the world where the atmosphere is humid : but 

 they are far more common in temperate climates than in the tropics. They are amoug 

 the first vegetables that clothe the soil with verdure in newly-formed countries, and 

 they are the last that disappear when the atmosphere ceases to be capable of nourish- 

 ing vegetation. The first green crust upon the cinders of Ascensiou consisted of minute 



