The Origin of Land Plants lit 



fectively protected from external vicissitudes, and, 

 moreover, during its development can draw upon 

 the parent plant for an unlimited supply of food. 

 It moreover is able to store up in the ripe seed the 

 reserve food necessary for its growth during the 

 early stages of germination. The advance of the 

 resting stage of the plant, from the simple spore in 

 the fern to the embryo within the seed of the seed- 

 plants, gives the latter a great advantage in the cer- 

 tainty and rapidity with which the new generation 

 can be established. 



It is positively known that the development 

 of seeds has taken place quite independently in 

 several groups of pteridophytes, and this makes 

 it likely that all of the existing seed-plants are 

 not necessarily descended from a single stock. 

 There is no question of the origin of the cycads 

 and Ginkgo from ferns of some kind, but the 

 evidence of the origin of the other seed-plants from 

 the same source is not so convincing. It has re- 

 cently been argued by Professor Seward that Arau- 

 caria, one of the conifers, shows strong evidence of 

 a relation with the tree-like club-mosses of the Coal 

 Measures, and there is much to be said in favor of 

 the derivation of the conifers from quite different 

 forms from those which give rise to the cycads. 

 All of the so-called Gymnosperms, i.e., conifers, 

 cycads, etc., show unmistakable evidences of hav- 

 ing originated from some pteridophytic ancestors, 

 but the origin of the higher type- of seed-plants, the 



