182 



MORPHOLOGY. 



135 



necessarily extend throughout the whole 

 length. It is mere prejudice to regard 

 the external peristoma as appertaining to 

 the external, and the inner peristoma as 

 appertaining to the inner, membrane. 

 The anatomy of most Moss capsules near 

 a state of maturity* shows evidently that 

 the peristoma and walls of the theca do 

 not stand in any nearer relation to each 

 other than as cells to the parts of a plant 

 generally. This may be plainly seen, for 

 instance, in the section, cut lengthwise, 

 of an unripe capsule of Grimmia apo- 

 carpa (fig. 135.). Starting from a one- 

 sided and false view of the ripe fruit, 

 botanists have accustomed themselves to 

 regard all these anatomical individualities 

 as especial organs, and then to seek for 

 methodical arrangement for them; whilst 

 the true mode of observation shows us that 

 we have to do here with merely tolerably 

 regular remnants of a torn organ. If, in- 

 stead of inventing supposititious theories, 

 pains had been taken to carry out inves- 

 tigations with somewhat more exactitude, it would soon have been dis- 

 covered, at least in the inner peristoma, that there was no room here for 

 many of the very ludicrous hypotheses broached regarding the subject. In 

 the peristoma we must distinguish whether the third upper portion of the 

 archegonium occupies a considerable part of the whole length, so that the 

 peristomse may be developed into vertical rows of cells, as in most cases, or 

 whether, as in the Polytriclioidece, &c., it is merely the flat upper portion 

 of the theca, and is therefore rather a development in horizontal layers. 

 Here, then, the inner peristoma or the membranous expansion of the 

 columella are the same thing, and formed from one layer of cellular 

 tissue. In others, on the contrary, a simple (?) layer is developed into the 

 inner peristoma, directed inward from the wall of the operculum ; on 

 this first layer another follows, directed inward, the cells of which on a 

 section all, or the alternate ones, resemble acute equilateral triangles, the 

 bases of which are directed alternately outward or inward. In these 

 cells the horizontal and the lateral vertical partitions become especially 

 thickened, while the external and internal walls, on the contrary, become 

 blended with the superjacent cells, and then separate subsequently from 

 the other walls : thus the plaited membrane in Buxbaumia, Diphyscium, 

 &c. is formed with some degree of regularity. If, on the other hand, 

 cells that on a section appear uniform alternate with others (Hypnum 

 abietinum, figs. 134. 136.), the persistent lateral partitions of the former 



* Compare the remarkably beautiful delineations of H. Mohl, loc. cit. 



183 Grimmia apocarpa. Section, lengthwise, through an unripe sporocarp. The cells 

 are only marked upon the right side, a, The operculum ; b, the teeth of the simple 

 peristoma ; c, the epidermis ; d, the external, e, the middle layer of the wall of the 

 theca, the former consisting of elongated, and the latter of very loose, cells; /, the 

 innermost layer of the wall of the theca, bounding the space (g) in which lie the 

 spores; h, external layer of the columella, likewise bounding the spore cavity ; f, the 

 cellular tissue of the columella, tolernbly loose. 



