[macallum] semi-centennial OF THE ORIGIN OF SPECIES 181 



Tlie heat and acrimony of the conflict are now but a memory, and 

 we are of a generation which takes evolution more or less for granted. 

 In consequence of an uncritical reception of the doctrine, almost as if 

 it were part of the air we breathe, there are few of our representative 

 thinkers who can give as good reason for the faith that is in them as 

 was the case with many of the former generation. It is, as Huxley said 

 in 1880, the customary fate of new truths to begin as heresies and end 

 as superstitions; and he went on to add, that as matters then stood it 

 was hardly rash to anticipate that, in another twenty years, the new 

 generation, educated under the influences of that day, would be in danger 

 of accepting the main doctrines of the " Origin oC Species '"' with as 

 little reflection and, it might be, with as little justification as so many 

 of liis contemporaries twenty years earlier rejected them. 



What Huxley anticipated has come about. The philosopher, the 

 historian, the journalist, the chemist, the physicist, the geologist and 

 even the theologian, accepts without as much as a superficial critical 

 examination the theory of evolution. Only amongst two classes is there 

 any tendency to question the validity of the theory. One of these classes 

 includes those whose religious creed is utterly opposed to evolution in 

 any form, and who would only accept the theory when it came to them 

 as a dogma to replace a discarded part of their creed. 'The other class 

 comprehends not only biologists but also all those who have intellectual 

 curiosity and exercise it in this line. To this latter class the doctrine is 

 ever on its trial, and it is well for the development of human thought 

 that it is so. 



To this class the theory in the last few years has seemed to lose 

 ground. Mendelism, De Vries' mutation theory and Weismann's 

 theory of the continuity of the germ plasma all appeared to undermine 

 the cardinal points in the theory, and in consequence one hears and 

 reads now and then that the theory is exploded. 



Nothing could be farther from the truth. What effect Mendelism 

 may have on the doctrine is yet to be known but so far it appears to 

 leave it where it was. 'The mutation theory is to the effect that rapid 

 and very important variations may occur, and thus the production of 

 one species from another may arise by the " saltation " method, instead 

 of developing by the slow method which Darwin postulated and which 

 the mass of evidence seems to indicate. That mutation may occur in a 

 few forms seems to be conceded, but it is exceedingly doubtful if it is a 

 general factor in species-making. 



In only one respect have Darwin's views apparently failed to find 

 acceptance in recent years. This was in the theory of heredity known as 

 Pangenesis. 'This theory was not propounded in the " Origin of Spe- 



