1 6,6 THE LIVING CYCADS 



described for any seed plant, its swimming sperms being 

 more numerous than in some of the ferns ; but the female 

 gametophyte is the most advanced yet described for 

 any cycad, approaching the condition shown by Wel- 

 witschia. 



It used to be assumed that characters indicating 

 relationship would be found only in those plants which 

 are near the place where the branch originated from the 

 main stock, and no doubt this is a good place to examine. 

 But the same assumption would lead to the conclusion 

 that a plant in a side branch having an important char- 

 acter, which it has inherited from the main stock, is 

 necessarily near the place where the branch originated. 



Such a conclusion would often be incorrect. Botan- 

 ists now quite generally agree that the monocotyls have 

 been derived from the dicotyls, and that the point of 

 origin is the order Ranales, of which the buttercup, 

 anemone, and crowfoot are familiar examples. It is true 

 that dicotyls with one " cotyledon and monocotyls with 

 two are rather frequent near this supposed origin of the 

 branch; but some of the most striking examples of 

 monocotyls with two cotyledons are found as far up 

 in the monocotyl series as the liKes, which in other 

 features have diverged most widely from the dicotyl 

 type. 



In typical dicotyls the wood is in a zone surrounding 

 the pith, while in monocotyls the woody strands are 

 scattered, as in a cornstalk; but here again there are 

 some species in the lily family which have the wood in 

 a compact zone surrounding the pith. These species 

 have persistently retained this dicotyl feature, while 

 they have diverged in others. 



