36 OUR NATIVE FERNS AND THEIR ALLIES. 



isosporous, producing spores of one kind ; and the heterosporous, 

 producing spores of more than one kinds* 



96. Germination. The germination of Lycopodium is 

 only partially known, as the prothallia have been seen in only 

 three species, and in these they have not been carried through 

 all the stages of development. That of L. annotmum is a yel- 

 lowish-white mass of tissue with a few small root-hairs.t The 

 antheridia and archegonia are developed from the upper side 

 of the prothallium. In L. cernuum, TreubJ found the pro- 

 thallia much smaller (one twelfth of an inch long), vertical in 

 growth, yellowish below and bright green above. The anthe- 

 ridia and archegonia are found round the summit of the cylin- 

 dric prothallium. 



97. The germination of Selaginella is better known. The 

 contents of the ripened microspores are transformed into a 

 mass of tissue consisting of a few cells, one of which remains 

 sterile and is considered a rudimentary prothallium, while the 

 others give rise to antherozoids, and are consequently considered 

 as a rudimentary antheridium. The macrospores, on the other 

 hand, produce a many-celled prothallium, which develop a few 

 root hairs and numerous archegonia, which after fertilization 

 give rise to a new plant. Two plants are sometimes produced 

 on the same prothallium. 



98. The microspores are thus seen to be male and the 

 macrospores female, showing a clearer differentiation of sex 

 in the products of the mature plant than appears in any other 

 group of the fern allies already studied. This may be consid- 

 ered a foreshadowing of the completely differentiated sexual 

 organs which occur in the flowering plants. In the method of 

 formation of the embryo the Selaginella also differs from all 

 other plants of this group, and approaches the flowering plants. 



* This division, though used by some of the best botanists, is at best an 

 artificial classification, as it separates genera otherwise closely allied to each 

 other. 



t Cf. J. Fankhauser, Botanische Zeitung, 1873, pp. 1-6; Bruchmann, 

 Botanisches Centralblatt, xxi (1885). 



\ Cf. Treub, Ann. d. Jard. Bot. d. Buitenzorg, IV (1884), 



