346 XXV. REPRODUCTION OF THE BRYOPHYTA. 



truded contents of older antheridia opened by the section prove 

 to be composed of rounded cells, still adhering together, the 

 mother-cells of the spermatozoids, in which the thread-like body 

 of the spermatozoid is already often recognisable. The 'chloro- 

 phyll grains at the apex of ripening antheridia assume a some- 

 what brownish tone. Emptied antheridia are open at their apex. 

 The paraph yses are simple cell-rows, the cells of which gradually 

 enlarge upwards, when they are, however, at least the uppermost 

 again tapering ; hence the uppermost cell is always pointed. The 

 walls of the cells are often browned in the lower part of, and not 

 infrequently even higher up upon, the paraphyses ; they contain 

 chlorophyll. Cross-sections through the lower part of the flower 

 show in an instructive manner the distribution of the antheridia, 

 their relations with the perichaetial leaves and the paraphyses r 

 and also provide us with numerous cross-sections through the 

 antheridia. 



Male Flowers of Polytrichum. Still more striking than the 

 male flowers of Mnium are the red-coloured ones of various- 

 species of Polytrichum, likewise found in May and June. For 

 examinationj we choose Polytrichum juniperinum. The outer 

 leaves forming the perichaetium, beyond their colour, further differ 

 from the ordinary leaves in that their unilamellar sheathing 

 portion is continued up to the apex of the leaf. The green 

 lamella, 1 characteristic of the genus Polytrichum, are found only 

 towards the end or apical portion of the leaf, and almost always 

 confined to the midrib. On the rapidly-decreasing reddish-brown 

 perichaetial leaves, near the 'interior of the flower, the green 

 lamellae are developed only on the extreme, sharply outward- 

 bent points. The leaf thus appears ultimately \ reduced almost to- 

 its sheath portion alone. The antheridia and paraphyses stand 

 in the axils of the perichaetial leaves. The middle of the flower is,. 

 however, occupied by a vegetative bud, into which the central 

 bundle of the stem is continued. Thence arises the later growth 

 through the male flowers (proliferation), which is normal for 

 Polytrichum. The antheridia have the same structure as in 



lr The leaves of Polytrichum, though really unilamellar, like those of 

 other mosses, are rendered opaque by being more or less covered by vertical 

 green scales, or lamellae, produced upon their upper side. In P. juniperinum 

 each foliage leaf shows about forty-eight such lamellae, running, as usual,, 

 longitudinally, and from four to six cells long. [Eo.] 



