10 INTRODUCTION. 



6. A consolidation of parts among each other 

 or with another circle, indicates a progress ; be- 

 cause they are originally separate. 



7. The more the structure of parts deviates 

 from the original, the more advanced it must be 

 considered. The four circles of the flora] parts are 

 a proof of progress in themselves, as petals are 

 more distant from the original structuie than sep- 

 als, stamens more than petals, etc. 



This law becomes most apparent in the ovary, 

 where the single seed leaf can be followed through 

 all its evolutions. The least differentiated, and in 

 consequence lowest form, is the ovule-bearing bract 

 of the Cycadaceae. In the Angiosperms a long se- 

 ries of evolutions may be traced. 



First, the simple Follicle, only to be distinguish- 

 ed from a rolled-in leaf with clasping margins, by 

 its function ; then the Legume, with a second de- 

 hiscence splitting the midrib of the seed-leaf ; then 

 the Drupe, where the three layers of the leaf be- 

 come changed in a peculiar manner. It would 

 occupy too much space to follow the evolutions of 

 the compound ovary from the distinct seed leaves, 

 through the septicidal, to the loculicidal, and sep- 

 tifragal capsule, to berry, pomum, etc. 



Besides the line of ovarian evolutions, we have 

 here to consider another which hides its progress 

 under an apparent depauperation or retrogression. 

 The transformation of the seed-leaf takes the 

 course of consolidation. The first step is the 

 Schizocarp, and its varieties Lomentum, and Coc- 



