420 The American Naturalist. [May, 
with field and laboratory data are placed paleontological data, 
as wellas l, including the unique facts of human 
variation and the laws of human inheritance. For in modern 
embryology certainly the most brilliant discovery is that the 
physical basis of all inheritance is the same—and growing out 
of this is the high probability that the laws of heredity are 
the same in the whole organic world, with no barriers between 
protozoa and metazoa, or between animals and plants. Both 
Weismann and Spencer show themselves blind to this nexus 
of fundamental uniformity when they draw certain lines of 
division in inheritance where none exist in the visible heredi- 
tary mechanism of chromatin and archoplasm. With these 
discoveries in mind does not Weismann appear as much afield 
when he maintains that the inheritance of acquired characters 
is a declining principle in the ascent of life, as Spencer when 
he maintains that it is a rising principle in the ascent of life? 
The first step then towards progress is the straightforward 
confession of the limits of our knowledge and of our present 
failure to base either Lamarckism or Neo-Darwinism as uni- 
versal principles upon induction. The second is the recogni- 
nition that all our thinking still centers around the five work- 
ing hypotheses which have thus far been proposed ; namely, 
those of Buffon, Lamarck, St. Hilaire, Darwin, and Nägeli. 
Modern criticism has highly differentiated, but not essentially 
altered these hypothetical factors since they were originally 
conceived. Darwin’s ‘survival of the fittest’ we may alone 
regard as absolutely demonstrated as a real factor, without com- 
mitting ourselves as to the ‘ origin of fitness.’ The third step 
is to recognize that there may be an unknown factor or factors 
which will cause quite as great surprise as Darwin’s. The 
feeling that there is such first came to the writer in 1890 in 
considering the want of an explanation for the definite and 
apparently purposeful character of certain variations? Since 
then a similar feeling has been voiced by Romanes and others, 
and quite lately by Scott ;* but the most extreme expression 
3 Op. cit., 1891. 
t On Variations and Mutations. Am. Jour. Sc., November, 1894. 
