EVOLUTION OF SEED-PLANTS 99 



complex, a change in which the increasing multi- 

 plicity of insect life was no doubt a chief factor. 

 The Angiosperms, arising probably as an off- 

 shoot from the Cycadophyte stock, thus found 

 their opportunity and rapidly fitted themselves 

 into the numberless new places that the chang- 

 ing world presented to them. The higher mem- 

 bers of the old family were no longer able to com- 

 pete with their more enterprising younger line; 

 the ancient race decayed, and, for all we know, 

 became extinct; the less advanced Cycads did 

 not come into such direct competition with the 

 ascendant race, and have survived, in moderate 

 numbers, as the recent Cycadacese. 



A Mesozoic genus of Cycads, Nilssonia, of 

 uncertain family, is known to have come down 

 to late Tertiary (Miocene) times, in the island 

 of Saghalien; Professor Nathorst suggests that 

 Nilssonia may possibly still survive in China. 



We will now pursue our inquiry a stage fur- 

 ther back, and endeavour to trace the origin of 

 the Cycadophyta themselves. 



Both the great branches of the Cycad stock 

 still show clear marks of affinity with Ferns, 

 a fact which has long been recognised by bota- 

 nists. As regards the recent Cycadacese, the 

 mode of fertilisation (by multiciliate sperms), 

 the arrangement of the pollen-sacs on the stami- 

 nate scale, the circinate coiling of the young 



