POLYTRICHUM. 



[ 527 ] 



POLYTRICHUM. 



includes the forms separated in this work 

 underCATHARiNEA, which in the 'Bryologia 

 Britannica' are divided between ATRICHUM 

 and OLIGOTRICHUM. The species of Poly- 

 trichum comprised in our definition are dis- 

 tributed in the same work under Pogonatum 

 (those with a round capsule and thirty-two 

 teeth) and Polytrichum proper (those with a 

 square or prismatic apophysate capsule (fig. 

 605 ), and usually twice as many teeth). 



Fig. 605. 



Fig. 606. 



Polytrichum commune. 



Capsule with operculum. Section of young capsule, 

 Magnified 10 diameters. showing the plaited spo- 



rangia! membrane. 



P. commune is one of our finest Mosses, com- 

 mon on heaths, moors, and mountain tracts, 

 varying somewhat under the different phy- 

 sical conditions. The stems are from 6" to 



Fig. 607. 



Fig. 608. 





Polytrichum commune. 



Fragment of peristome. Columella with section 



Mag . 100 diams. of the apophysis. 



Magn. 25 diams. 



1' long, and the fruit-stalks 2 or 3". The 

 stems are almost of woody texture, the leaves 

 large and firm. The calyptra is densely co- 

 vered with hairs. Wilson remarks that the 

 true structure of the sporange and columella 



Fig. 609. 



Fig. 610. 



Polytrichum commune. 



Sterile inflorescence. Innovation from sterile 



One-half nat. size. inflorescence. 



Magn. 5 diams. 



of Mosses may be most easily learned from 

 the study of this genus. The columella 

 (figs. 606, 608) is seen to be separated from 

 the spores by an inner layer of the spo- 

 rangial membrane. The diaphragm attached 

 to the apices of the teeth of the peristome is 

 the dilated apex of the columella (fig. 608). 

 The peristome (fig. 607) is composed of 

 ligulate obtuse teeth, connected by a mem- 

 brane at the base, continuous with the inner 

 layer of the wall of the capsule. These 

 plants are also exceedingly well adapted for 

 the examination of the male inflorescence 

 and spermatozoids. They are all dioecious, 

 and the male plants (fig. 609) are readily 

 distinguishable by the cup-shaped inflores- 

 cence, composed of scale-like leaves and 

 paraphyses surrounding a number of subu- 

 late sacs constituting the antheridia. The 

 male flowers of P. commune, juniperinum, &c., 

 are found everywhere on heaths in spring. 

 The antheridia may be readily extracted un- 

 der a simple lens, and when placed in water 

 under the compound microscope, soon (if 

 ripe) burst at the summit and discharge the 

 spermatozoids; these usually escape still 

 enclosed in their parent-cells, which when 

 first discharged cohere in a gelatinous mass, 



