386 



MOSSES AND FERNS 



CHAP. 



edly from the other genera in the form of the prothallium, 

 which is filamentous and extensively branched, resembling very 

 closely that of certain species of Trichomanes (Fig. 222, B, C). 

 The antheridia resemble those of Aneimia, but the archegonium 

 has the straight neck found in the lower Leptosporangiatse. 



The Sporophyte 



The tissues of the sporophyte in Lygodium and Schizaa, are 

 much like those of Gleichenia and the Hymenophyllacese. As 

 in these the stem as well as the petiole is traversed by a single 



FIG. 224. Lygodium Japonicum. A, Pinnule, Xs; s, the sporangial segments; B, 

 horizontal section of one of the latter showing the sporangia, sp, Xi4; C, a single 

 sporangium, showing the terminal annulus (r), X6s; cross-section of the petiole, 

 X6 5 . 



concentric vascular bundle. In most species of Aneimia and 

 Mohria the bundles of the stem form a cylindrical network like 

 that of the Polypodiacese. The stem bundles are concentric, 

 as are those of the petiole and larger veins in all but Schis&a, 

 which Prantl ( (5), p. 23) states has collateral bundles through- 

 out, except in the stem. The small veins have collateral bun- 



