Nov. 1, 1867.] 



HARDWICKE'S SCIENCE-GOSSIP. 



253 



of cells, the outer of which becomes indurated at 

 maturity, and often richly coloured. 



Enclosed within the capsule is the Sporangium, 

 or Spore sac, consisting of two strata of cells, the 

 outer of which is contiguous to the lining membrane 

 of the capsule, or is suspended from it by delicate 

 threads ; the inner is united to a pillar, occupying the 

 central axis of the capsule, and named the Columella, 

 the apex of which joins the lid, and sometimes falls 



Fig. 2;3, 



Section of Fruit of Funaria, showing Sporangium 

 suspended by threads. 



Fig. 274. Section of upper part of fruit of Mnium hornum, 

 a. wall of capsule, b. annulus, a. lid, d. tooth of outer peri- 

 stome, e. tooth of inner peristome,/, cavity of sporangium 

 and spores, g. Columella. 



away, the mouth of the capsule is seen, sometimes 

 naked, when it is termed gymnostomous, but 

 usually adorned by the beautiful appendage named 



away with it, though occasionally we see the 

 columella projecting from the mouth of the capsule 

 like a style (figs. 273, 274). The lid having fallen 



the Peristome, consisting of curious hygroscopic 

 tooth-bke processes in a single or double series. 



The simple peristome, or the outer one when 

 double, originates from the lining membrane of the 

 capsule ; its teeth are always constant in number, 4, 

 8, 1G, 32, or 64, and present an infinite variety of 



Fig. 275. Part of inner and outer peristomes of same. 



forms (figs. 277, 278, 279). They consist of two 

 strata of cells, the outer in two rows, transversely 

 jointed (trabeculate), richly- 

 coloured, aud often separated 

 for a part of their length, in 

 the central or divisural line ; 

 the inner in one row, thin 

 and hygroscopic, and projecting 

 inward as transverse lamellae 

 (figs. 275, 276, 2S0). In the Polytrichace*, how- 

 ever, they are quite different, and consist of a mass 

 of agglutinated filaments, and Mr. Mitten uses this 



Fig. 276. Transverse 

 section of tooth of 

 outer peristome. 



Fig. 277. Fruit of Tetraphis 

 pellucida. peristome of 

 lour teeth. 



Fig. 278. Splachnum sphsericum, 

 with eight bigeminate teeth, 

 and exserted columella. 



distinction to separate all mosses into two sec- 

 tions, Arthrodonti, those with jointed teeth, and 

 Nematodonti, those with filamentous teeth. Iu the 

 Polytricha, also, the top of the columella is dilated 

 into a membrane, closing the mouth of the capsule, 

 and joined to the points of the teeth ; this expan- 

 sion has been named the epiphragm or tympanum 

 (fig. 280). 

 The inner peristome takes its origin from the 



