SYSTEMATIC BOTANY. 



101 



indication of a fibro-vascular system. The two classes, into 

 which the Bryophytes are divided, are the Liverworts {Hepat- 

 icx, Fig. 126), and the Mosses (Miisci, Fig. 125). 



Collect as many kinds of Mosses as can be found in fruit, i. e. with the 

 (usually long) pedicels surmounted by the capsules. Sketch the entire plant, 

 natural size. Then use the lens and make magnified figures of leaves, also 

 of the capsule and all that can he seen in connection with it. Liverworts 

 are less common, hut specimens may be found on damp shaded rocks. For 

 herbarium specimens (which should, especially in case of the Mosses, show 

 the fruit), dry between sheets of soft paper ; then put in pockets or glue 

 direct to the herbarium sheets. 



16. The next division, Pteridophjrtes, includes the Vas- 

 cular Cryptogams, namely the Ferns 

 and their allies. Here as in the previ- 

 ous division there is an alternation of 

 sexual and non-sexual generations. 

 But while the conspicuous generation 

 (the Moss) in the Bryophytes is sexual 

 and the inconspicuous, namely the 

 sporangium, non-sexual, the reverse is 

 the case in the Pteridophytes. That 

 is, the conspicuous generation (the 

 Fern, etc.) is non-sexual; and the 

 sexual generation or stage (the pro- 

 thallium), that bearing the sexual re- 

 productive organs, is very much re- 

 duced and short-lived. This prothallium is a small, flattened, 

 thallus-like growth from the spore, composed of chlorophyll- 

 bearing parenchymoup cells, in one or a few layers ; on its under 

 surface are produced rhizoids,by which it is fixed to the ground. 

 On the prothallia are developed the archegonia and antheridia, 

 which are essentially similar to those in the higher plants of 

 the preceding division. The spirally-coiled spermatozoids 

 escape from the antheridium, enter the tube or neck of the 

 archegonium, and fecundate the germ-cell therein contained. 

 The protoplasm thus fecundated begins a course of develop- 

 ment resulting in the formation of a young plantlet, which 



Fig. 126. 



