266 THE AMERICAN NATURALIST. . [Vor. XXXVI. 
It appears that. von Waagen suggested the term “ mutation ” 
for immeasurable variations somewhat similar to these. Scott 
in 1891 (91, p. 388) pursued the idea further in the following 
striking passage: “ These facts.at least suggest the possibility 
that individual variations are not incipient species, but that the 

Fic. 5. — Superior molars of primates. 4, Adapis; B, Hyopsodus; C, Notharctus. Showing 
homoplastic cusps, Ay, m/, ps, ms, mts. 
causes of transformation lie deeper, and act with more or less 
uniformity upon large numbers of individuals. It may, per- 
haps, be the outcome of future investigations, that while varia- 
tions are generally due to the union of changing hereditary 
tendencies, mutations are the effect of dynamical agencies 
operating long in a uniform way, and the results controlled by 
natural selection. While this may be true, a great many facts 
must be gathered in its support, before it can be regarded as 
more than a suggestion." Scott subsequently, in his article 
“Variations and Mutations,” expanded this idea: * Bateson's 
results, as compared with those of paleontology, confirm this 
distinction in many significant ways and emphasize strongly 
the difference between variation and that steady advance along 
definite lines which Waagen called mutation." This paper in 
turn is said to have influenced de Vries's recent work, Die 
Mutationstheorie. 
It is a singular coincidence that the human teeth were 
selected by both Empedocles and Aristotle to test the “ survival 
of the fittest" versus the purposive or teleological theory of 
evolution. I pointed out in the papers above referred to 
(Osborn, '89, pp. 561—566; '90) the significant fact that new 
cusps of the molar teeth do not appear at random, but at 
certain definite. points; that they are at first so minute that 
