446 INTRODUCTION TO CETPTOGAMIC BOTANY. 



490. They grow in moist shady places, on the ground, the 

 trunks of trees, leaves, &c., and occasionally on objects ex- 

 posed to the sun, provided there be sufficient moisture. Some 

 will, however, bear considerable drought without injury. The 

 fruit proceeds at once from the stem without any intermediate 

 receptacle, except the point from which it springs, which is 

 sometimes slightly swollen or depressed, and is then called the 

 torus. It is remarkable for its almost constantl y splitting into 

 four equal valves, in which respect a close approximation was 

 made hjLunularia (Fig. 93, d, e). A few exceptions will be 

 'noted as we proceed. The peduncle is surrounded at the base 

 by various membranes, the details of which constitute the dis- 

 tinguishiug generic characters.* In Anthocerotem there is a 

 distinct columella, the first iadication of the complication of 

 the organs of fructification which obtain so high a develop- 

 ment LQ the mosses. The spores do not produce a prothallus 

 as in Ferns and Clubmosses, but the plant arrives at its full 

 development before the archegonia appear, which go through 

 the different stages of growth up to the perfect development 

 of the spores, much after the manner of Marchantiacece, and 

 the same plant may produce more than one crop of archegonia. 

 The elaters, as in Marchantia (Fig. 92, e), are produced from 

 narrow cells iaterspersed amongst those which produce the 

 spores, either longitudinally or transversely, and are often per- 

 manently attached to the valves. The male fruit is variously 

 disposed, consisting of short, often ovate, masses of cells, each of 

 which contains a spermatozoid resembling those which have been 

 figured above (Fig. 91,/). The spermatozoids were first disco- 



* It may be useful to enumerate the parts which occur in Junger- 

 mannics. The sporangium is the innermost, which may be confluent 

 with the swollen archegonium or calyptra, and is then tipped with the 

 styleshaped summit of that organ. The swollen archegonium is, how- 

 ever, mostly free, and forms a distinct sac round the sporangium ; in 

 proportion as it is sunk into the torus, it bears the abortive archegonia, 

 if more than one is present, on its surface or at its base. The perianth 

 or proper involucre then follows, which may be more or less confluent 

 with the calyptra. And this, again, may be surrounded by the external 

 involucre and perichsetial leaves (Kg. 95, c). 



