158 KANSAS ACADEMY OF SCIENCE. 



erect lamellae on the upper surface, and vary in number from two to eight. 

 These lamellae also vary in their height from 4 to 13 cells high, in some 

 species. 



The leaves of most mosses are but one layer of cells in thickness; some 

 are two or even three layers thick; while the shape, size, and arrangement of 

 the cells, termed the areolation, varies widely in different families, consti- 

 tuting a basis of classification used by all modern bryologists. 



The shape and size of the cells may vary from minute hexagonal or 

 rectangular to large hexagonal or rectangular, rhomboidal, or very long 

 linear, flexuous, or vermicular, according as the areolation is dense or loose. 

 Sometimes the cells are very densely chlorophyllose, as in Atrichum, Timmia, 

 etc.; or the cells may contain but few large chlorophyl grains, as in Mnium, 

 Bryum, and others; again others are without any chlorophyl (hyaline), as in 

 Leucobryum and Sphagnum, having then a whitish appearance. (See plate 

 V.) The basal cells very frequently differ from the upper cells, either in 

 size, shape, color, or in being hyaline, when the upper cells are chlorophyllose, 

 or the reverse. This variation of the basal cells is often used as a specific 

 distinction, and Schimper uses this feature, especially in the genus Dicranum, 

 dividing it into two sections. 



When the ends of the cells are rectangular, they are termed parenchymatous, 

 as in some of the Hypna. (See plate XXIV.) When elongated, and pointed or 

 rhombic, the aerolation is prosenchymatous, as in Bryum, and some Hypna. 

 (See plates XXX and XXXII.) Sometimes the walls are very much thickened, 

 producing only a point or dot, as in Grimmiaceae. 



Reproduction is accomplished both sexually and asexually. The asexual re- 

 production is accomplished in many ways; but in almost every case a new plant 

 is preceded by a protonema. In some mosses the leafy buds, becoming detached, 

 or the leafy branches broken from the stem, grow immediately into new plants 

 upon striking the soil; as in Conomitrium julianum, and Cinclodotus aquaticus. 

 A single protonema may produce many plants; or single cells of the protonema 

 may become globular, separate fi-om one another, and lie dormant until next sea- 

 son, as in Funaria hygrometrica, each then growing into a new protonema. The 

 rhizoids, either the aerial or subterranean, may change directly to protonemal 

 threads, as in Bryum, Mnium, Barbula, etc.; or by first forming tubercles con- 

 taining stored food material, which remain dormant until exposed to light, heat, 

 and moisture, when they develop into protonema, as in Barbula muralis, Funa- 

 ria hygrometrica, Grimmia pulvinata, Trichostomum rigidum, and Atrichum. 

 (See plates XIV and XXII; see also in Goeble, p. 172.) The aerial rhizoids may 

 produce protonema, with chlorophyl in their cells, and leaf buds directly; and 

 Schimper says the annual male plants are produced in this way by the perennial 

 patches of female plants of Dicranum undulatum, thus accomplishing their fer- 

 tilization. The cells of leaves may produce protonema by growing out into tubes 

 which become segmented into propagula, as in Orthotrichum lyelli, O. obtusifo- 

 lium, etc. Club-shaped penicillate tufts of protonema, with short cells, grow on 

 the tips of the leaves of Orthotrichum phyllanthum, Grimmia trichophylla, Syr- 

 rhopodon, and Calymperes. Protonema may grow from some leaf tips, fi-om the 

 marginal cells of leaves, as in Buxbaumia aphylla, or fi-om the tips of fertile 

 plants, as in Leucobryum vulgare. The setae or cell walls of the capsule will 

 produce protonema, and also the inner surface of the calyptra of Conomitrium 

 julianum. 



Gemmae as well as spores produce new protonema, hence new plants. The 

 gemmae are little spherical cellular bodies containing chlorophyl, which are pro- 



