AND THE APE THEORY. 39 



to man. In this, as in all researches into the deriva- 

 tion of our organism, we must distinguish between 

 the general theory of descent and the specific hypo- 

 tlusis of descent. The general theory of descent 

 claims full and permanent value, because it is induc- 

 tively based on the whole range of common biological 

 phenomena and on their internal causal connection. 

 Each special hypothesis of descent, on the other 

 hand, is conditional as to its specific value on the 

 existing state of our biological information, and on 

 the extent of those objective empirical grounds on 

 "which we deductively found the hypothesis, by our 

 subjective inferences." And I must here emphatically 

 add that I have on every opportunity repeated that 

 reservation, and have always insisted on the difference 

 which exists between the absolute certainty of trans- 

 mutation in general and the relative certainty of each 

 individual specific pedigree. So that when Semper 

 and others of my opponents assert that I teach my 

 specific genealogies as " infallible dogmas," it is 

 simply false. I have, on the contrary, pointed out 

 on all occasions that I regard them only as heuristic 

 or provisional hypotheses, and as a means of investi- 

 gating the actual relations of cognate races of organic 

 forms more and more approximately. 



Since the conception of the natural animal sys- 

 tem as a hypothetical genealogical tree, and the 



