80 PRESIDENTIAL ADDRESS SECTION C. 



10. Though somatically more plastic, prodophytes may be 

 germinally more rigid than hepophytes. This would explain why 

 new prodophytic species do not arise so frequently, and therefore 

 why prodophytic species are less numerous. Prodophytes, how- 

 ever, probably often give rise to new species which are hepophytic 

 and the reverse process may happen, also hepophytes producing 

 prodophytes. 



Many of these tentative conclusions require 'further testing. 

 They illustrate, however, how by using this very fruitful compara- 

 tive method, light can be thrown on the laws of communal develop- 

 ment or succession. Such laws, once they are established, are 

 clearly of the utmost importance. Had time permitted, I should 

 have liked to indicate how by analogy such laws of plant succession 

 supply fruitful ideas to those interested in the laws governing the 

 development of human communities. In South Africa the pioneers 

 (voortrekkers) can be compared with the men that belong to the 

 more complex communities that have now been built up, and many 

 interesting points are brought to light. That, however, is a subject 

 which could be more appropriately dealt with by our friends in 

 Section F. of this Association. 



Addendum. 



Since the above was written, in the last number of Ecology 

 (Vol. II., 2, 1921) A. A. Hansen has published a short paper on 

 "The Terminology of Ultimate Vegetation." He proposes tbe 

 term "eschatopbyte" for any member of an ultimate (or climax) 

 vegetation. This term would not be synonymous quite with 

 hepophyte, which includes plants belonging to intermediate as well 

 ;is final stages of succession. 



