336 



PART IV. VEGETABLE TAXONOMY. 



protonema, from which the leafy or thalloid plant is subsequently- 

 developed. 



In the majority of the Bryophyta, the distinction between 

 leaf and stem is clearer than in the Characese and other foliose 

 Thallophyta, but the leaves of Mosses are simpler in their struc- 



Fig. 541. 



Fig. 542. 



Fig. 544. 



Fig. 545. 



Fig. 541. — The common Hair-cap Moss, Polytricum commune, in fruit, a, stalked 

 capsule covered with a calyptra. 



• Fig. 542. — Capsule somewhat magnified, and with the calyptra removed, showing 

 operculum, a. 



Fig. 543. — Paraphyses and antheridia, one of the latter emitting antherozoids, a. 



Fig. 544. — Antherozoids, highly magnified. 



Fig. 545. — Female organ, or archegonium, highly magnified, a, oosphere. 



ture than those of higher plants. They often consist of a flat 

 expansion composed of a single layer of cells which are all alike, 

 but in a few species the cells are in more than one layer and one 

 or two simple nerves are developed. The stems, of the higher 

 forms at least, have an axial bundle of elongated, thin-walled 



