210 



SYMMETRY OF THE SPOROPHYTE 



construction, though possibly dorsiventrality may have existed among the 

 smaller forms. Of modern Lycopods, the mature shoots of Lycopodium 

 show in relation to their position the most gradual transitions from the 

 radial to the dorsiventral. The species of the sub-genus Selago, and 

 Sub-Selago maintain the radial construction, and are for the most part of 

 upright habit. The rest of the genus is very variable : the shoot is some- 

 times radial, as in L. i?mndatum : or distinctly distichous forms may occur, 

 such as /. Phlegmaria and nummularifolium, which are both pendulous 



A. 



B. 



FIG. 105. 



A, young sporophyte of Danaea simplicifolia still attached to the gametophyte, pr. 

 X 3. B, an older sporophyte of the same species. C, gametophyte of A ngiofiteris evecta 

 with young sporophyte. (A , B, after Brebner ; C, after Farmer, from Campbell's Mosses 

 and Ferns.) 



epiphytes. The change from the radial type may be apparent first in a 

 slight inequality of direction of the leaves, otherwise equal, as in the 

 creeping shoots of L. annotinum or davatum : or in the marked inequality 

 of their size and structure, as in L. complanatum or alpinum. Goebel 

 has shown a by experiment on L. complanatum that the dorsiventrality 

 is directly induced by light. Finally, the climbing species, /. volubile, 

 is specially characterised by a distichous form of the shoot not unlike 

 that usual in Selaginella. It has already been concluded on other 

 grounds that the Selago type of Lycopodium is the most primitive : it 

 is this same type which retains most constantly that radial construction 

 which there is reason to believe is a primitive character. 



1 Organography , vol. i., p. 252. 



