2 10 



SYMMETRY OF THE SPOROPHYTE 



construction, though possibly dorsiventrality may have existed among the 

 smaller forms. Of modern Lycopods, the mature shoots of I.ycopodium 

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

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

 Si//>-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. inundatum : or distinctly distichous forms may occur, 

 such as L. Phlegmaria and nummularifolium^ which are both pendulous 



B. 



Fit,. 105. 



A, young sporophyte of Danaea sitnplici/olia still atta< hed to the gametophyte, /*-. 

 X3- B, an older sporophyte of the .same species. C, gametophyte of Angiofrteris <TV, ',* 

 with young sporophyte. (A, B, after Hrebner ; C, after Fanner, from Campbell'* Mo 

 and P'crns. ) 



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 claratuin : or in the marked inequality 

 of their size and structure, as in /. complanatnm or alpinum. Goebel 

 has shown J by experiment on L. complanation that the dorsiventrality 

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

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

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

 grounds that the Se/ngo 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 Organograpky, vol. i., p. 252. 



