236 



THE GEOLOGICAL HISTORY OF PLANTS. 



fruits, and seeds belong to the more recent periods, and 

 simpler forms were at least dominant in the older times. 

 Yet even in this respect the great leading laws and struct- 

 ures of bisexual reproduction were perfected in the early 

 Palaeozoic, and the improvements introduced in the gym- 

 nosperm and the angiosperm of later periods have con- 

 sisted mainly in additions of accessory parts, and in modi- 

 fications and refinements suited to the wants of the higher 

 and more complex types. 



