OEGAXS OF EEPBODUCTION. 



Fig. 808. 



Fig. 809. 



Fig. 810. 



Fig. 808. Pottia tnmcata, showing the separation of the operculum from 

 the sporangium. From Henfrey. Fig. H09. Sporangium,?'., of Hair- 

 Moss deprived of its calyptra and operculum, p. Peristome, e. £pi- 



phragma or tympanum. Fig. 810. Transverse section of a sporangium 



of Hair-Moss, showing the columella surrounded uj- free spores. 



stretched across the mouth of the sporangium, and forms what 

 has been called the epiphragma or tympanum {fig. 809, e). 

 Wlien the mouth is naked, the Mosses in which such a sporan- 

 gium is found are called gymnostovious or naked-rnouthed ; when 

 the mouth is surrounded by a single row of teeth, the Mosses are 

 said to be aploperistomons ; or, when with two rows, they are 

 diploperistomous. The different appearances presented by the 

 teeth, as well as their number and degree of cohesion, form 

 important distinctive characters in the different genera of Mosses. 

 The operculum, as already stated, is formed by a projection of 

 the outer layer of the wall of the sporangium. At the point 

 where the operculum separates an elastic ring or annidtis is pro- 

 duced, which encircles the mouth of the sporangium. 



In germination, the inner coat of the spore is protruded as a 

 tubular process, which, as it elongates by cell-division, forms a 

 green cellular branched mass, or prothallium, like a Covferva. 

 As described by Berkley, "this mass is very much of the same 

 nature as the mycelium of Fungi, and is called the Protonoma, 

 and is always distinguished by the cells containing chlorophyll. 

 Many spores may concur in the formation of this mass ; but 

 whether more spores than one concur in the formation of a 

 single plant is doubtful. Be this as it may, after a time a little 

 knot or swollen articulation appears upon the threads, which, 

 by cell-division, is developed into a leafy shoot, upon which 

 archegonia and antheridia are afterwards developed." 



The archegonium of Mosses is regarded by Henfrey " to resem- 

 ble the so-called ovules of Club-mosses and Pepperworts — the 

 archegonium giving rise to sporangiferous individuals. There is 



