ALTERNATION OF GENEKATIONS IN MOSSES. 



479 



calyptra, see figs. 350^ and 350^). Ultimately this hood is thrown off and the 

 capsule, within which quantities of spores are produced, opens. The spores are 

 readily distributed by the wind shaking the capsule on its stalk. It should be 

 noted that in Mosses this asexual generation (the sporogonium) never becomes 

 independent of the sexual Moss-plant; the base of its stalk always remains embedded 

 in the tissues of the sexual generation. In the Ferns, on the other hand, the 



Fig. 351.— Alternation of Generations in Mosses. Various forms of sporogonium, which as the asexual generation 

 have been produced at the tips of leafy shoots. 



* Splachnum luteum. 2 Xa unripe capsule of the same. » A ripe and open capsule of the same. * Splachnum vasculosum. 

 *■ Longitudinal section of a ripe capsule of this Moss. ^ Splachnum ampullaceum. ? An unripe capsule, s a ripe 

 sapsnle of the same, a and 10 Schistostega osmundacea. " A ripe capsule of the same. 1, *. 6, 10 natural size ■ 2, 3 x 2 ; 

 '.«. «X10; " xl5; 5x100. 



asexual generation ( = the Fern-plant), though at first drawing nutriment from the 

 prothallium (cf. p. 475) by its " foot ", soon becomes quite independent, the prothal- 

 lium dying away. The form of the sporogonium is very varied in different groups 

 of Mosses. In fig. 351 are shown the sporogonia of a number of Mosses, including 

 •species of Splachnvmi (S. luteum, S. vasculosum, and S. ampullaceum.), a rare form 

 ■occurring on the excrements of cattle, reindeer, &c., that of the already-mentioned 

 Luminous Moss (Schistostega osTnundacea, cf. vol. i. p. 385); and in fig. 191, p. 16 



