MuscrN£:js 133 



vided with stomates, though these are frequently present on the organs 

 of propagation ; while one group of thalloid forms (Marchantiaceee) 

 possess stomates of remarkable and complicated structure. The vegeta- 

 tive propagation of the Muscineae takes place in several ways : ist, by 

 innovation, i.e. by a process of renewal at the apex, while the oldest parts 

 die off behind ; 2nd, by means of gemmae, stolons, or detached buds ; 

 and 3rd, by the non-sexual production of a thallus or protoneme, a 

 process which will be described presently. The facility of these various 

 modes of vegetative multiplication gives rise to the tufted or csespitose 

 habit of many species. 



Notwithstanding the variety in the development of the vegetative 

 structure, the sexual organs of Muscineae are remarkably uniform in 

 their main features. The male and female organs are termed respec- 

 tively, as in Vascular Cryptogams, antherids and archegones. The 

 mature antherid is a spherical, ellipsoidal, or club-shaped body, with a 

 longer or shorter stalk, the outer layer of its cells forming an enclosing 

 wall, while each of the small and numerous crowded cells in the interior 

 develops an antherozoid. These bodies are spirally-coiled threads of 

 protoplasm, thicker at the posterior end, and tapering to a fine point 

 at the anterior end, where they are furnished with two long fine cilia, 

 the vibrations of which set them in constant motion ; they are set free 

 by the rupture of the wall of the antherid at its apex. The archegones, 

 when in a condition capable of impregnation, are flask-shaped bodies 

 bulging from a narrow base, and produced above into a long neck. 

 The swollen or ventral portion, the venter, encloses one cell much 

 larger than the rest, the central cell, from the larger and lower portion 

 of which is developed, after its separation by a horizontal septum, the 

 germ-cell or oosphere. Above this central cell is an axial row of cells 

 termed the canal-cells, passing through the narrow portion or neck of 

 the archegone, and continued as far as the apical cells, stigmatic cells, 

 or lid-cells, which form what is called the stigma. These canal-cells 

 are transformed before impregnation into mucilage, which finally swells 

 up and forces apart the four stigmatic cells, an open canal being thus 

 formed, through which the antherozoids reach the oosphere. Notwith- 

 standing the general uniformity in structure of the sexual organs of the 

 Muscineae, their origin varies greatly. They may originate, in the 

 thalloid forms, below the growing apex, from the superficial cells of the 

 thallus, or oh special metamorphosed branches ; in the foliose forms 

 both antherids and archegones may be formed from the apical cell of 

 the shoot, or from segments of it ; and in this case they may take the 

 place of leaves, of lateral shoots, or even of hairs. According to 

 Leitgeb, the order of evolution from the lower to the higher forms of 



