HARD WICKE'S SCIENCE-GOSSIP. 



97 



GRAPHIC MICROSCOPY. 



By E. T. D. 



No, V. — Peristome of Funaria hygrometrica. 



HE urn-shaped cap- 

 sule, or pocket, 

 erect on the sum- 

 mit of its foot- 

 stalk, so often 

 seen by an ob- 

 server of growing 

 mosses, for struc- 

 ture and colour, 

 is to the micro- 

 scopist, and with- 

 out reference to 

 its deeper morpho- 

 logical interest, an 

 object of great 

 beauty. It is 

 impossible to ap- 

 proach the subject 

 in its amplitude, 

 but a concise ex- 

 planation of the plate is necessary. 



This well-known "moss cup" is the sporangium, 

 and in it are developed and contained the dust-like 

 spores, protected by an elegantly perforated or re- 

 ticulated tissue known as the peristome, which, in 

 some cases, is capable of unfolding, revealing and 

 releasing the reproductive atoms within. The whole 

 is often covered with a calyptra, or hood — a loose 

 extinguisher-shaped body which soon falls off; the 

 peristome is then seen in all its beauty, when un- 

 furled, as in Funaria, or as modified in other species, 

 the spores escape and fulfil their function. The 

 sporangium and its contents are the only product of 

 the true and normal fructification of the plant. In 

 some cases the spores are released by the decay of 

 the outer integuments. 



The sporangium under microscopic powers dis- 

 plays internally the most complicated structures, but 

 externally it is crowned by the peristome, which is 

 variously formed, either by fringes, well -fitting 

 lappets convoluting to a centre, or in some cases of 

 slits arranged round the margin, the structure ramifies 

 No. 233.— May 1884. 



into various alternations, their disposition being 

 factors in the distinction of genera. 



In the genus Bryum, a double peristome is found, 

 of great interest, in Neckera pumila, common on 

 trunks of trees ; the twin peristome is very singular, 

 the over and outer teeth curl back and show the 

 inner layer like a perforated dome, united by cross 

 bars — a microscopic exhibit of rare beauty. 



Much has yet to be discovered in bryology, but 

 the direct mode of germination from the spore, 

 elaborated in the sporangium, is safe ground. When 

 released the spore falls, and produces a confervoid 

 structure (the protonema). Much might be said of 

 the microscopical interest involved in this confervoid 

 filament. From the protonema a differentiation of 

 cells are evolved, from which proceed minute buds ; 

 each of these can hardly be said to grow, but they 

 are the nidus of a leafy stem, forming at last, a small 

 tufted group of vegetation, the foundation of " anthe- 

 ridia " and "archegonia." A magnification of not 

 less than thirty diameters is required for examination. 

 The reader may now be referred, for a further descrip- 

 tion of the ultimate development of the new plants, 

 to page 83 in the April number, where it is well de- 

 scribed by J. F. R., in " Notes for Science Classes." 



The strange and mysterious process there detailed 

 may be seen on the stage of the microscope, without 

 much difficulty. A good specimen for this purpose is 

 Polytrichtiin comT!ume, abundant on every heath, and, 

 at this particular season, in exactly the condition 

 required. In the interstices of a tuft of older plants 

 may be detected the minute objects sought for ; they 

 can be picked out with forceps and placed in a drop 

 of water, or, better, a saturated solution of chloride 

 of calcium, on a slip with a covering glass. The 

 latter medium is sufficiently deliquescent to preserve 

 an impromptu botanical preparation, with no other 

 care, for several days or weeks, without deterioration. 



In addition to the normal mode of fructification, as 

 described by J. F. R., there are subsidiary modes, 

 peculiarly abundant in mosses. The stems often 

 send out branches, which root, and produce buds. 



F 



