EVOLUTION OF SEED-PLANTS 127 



through the micropyle. This may be a primitive 

 character, but it does not seem to have been 

 general in the seeds of the Pteridospenns. The 

 only important peculiarity of the Palaeozoic 

 seeds is the absence of an embryo, indicating 

 that the nursing of the infant plant was a func- 

 tion which the seed did not take on till later times. 



In all other respects the seeds of the Peterido- 

 sperms were true seeds; the stages of their evo- 

 lution from the female sporangium, from which 

 we suppose them to have been derived, are still 

 to be discovered. Some light is thrown on the 

 question by another line of descent, that of the 

 Club-mosses or Lycopods, some of which pro- 

 duced a kind of seed, a subject to which we shall 

 return in Chapter VI. 



On the whole, the seed-bearing Ferns may 

 be regarded as showing a relatively early stage 

 in the evolution of Seed-plants, though the seed 

 itself was already so far advanced. We must not, 

 however, suppose that the Pteridosperms by any 

 means represented the highest stage of evolution 

 reached in the Palaeozoic Flora. 



A contemporary group, known to Science 

 long before the Pteridosperms were recognised, 

 attained a much higher development than they, 

 rivalling the Conifers of later periods. This was 

 the family of the Cordaitese; as regards some 

 forms of the type-genus, Cordaites, our knowledge 



