170 BOTANICAL GAZETTE [MARCH 
by slow and almost invisible changes as was assumed by DARwin. 
The theory itself does not, of course, depend on this or other single 
instances; it is founded upon general considerations taken from 
almost all branches of biological and paleontological research, as 
I have often pointed out." 
One of the main arguments is the statement that adaptations 
cannot, as a rule, have been produced by slow improvements, and 
that quite a large number of differentiations in organization, if not 
almost all the really important ones among them, are not adapta- 
tions at all. 
Apart from our poetical admiration of nature, we have no other 
way of judging the reality and efficiency of supposed adaptations 
than by their effects in the struggle for life. Species which are 
distributed over large countries and occur in thousands of indi- 
viduals are evidently well fitted for their life conditions. Newly 
introduced forms, which are spreading with astonishing rapidity 
and gaining a large territory often in the lapse of a few years, 
thereby show the highest degree of adaptation to their new environ- 
ment. But a showy differentiation may be followed by a wide 
distribution, as in the case of Drosera, or limit the species to a 
relatively very small area, as in Dionaea. 
Of late J. C. Wittis has brought forward the most conclusive 
evidence against the theory of natural selection and in favor of an 
origin of species by mutation.2 He bases some of his arguments 
upon his observations of the endemic species of Ceylon, such as are 
found in Coleus, Acrotrema, and other genera. If these endemics 
had evolved according to the law of natural selection, in consequence 
of a gradually increasing adaptation to their local environment, 
it would follow that they must now be better adapted than their 
parent types, conquer these in the struggle for life, and become 
quite common, while the old forms would tend to disappear. As 
a matter of fact, however, their behavior is quite the contrary. 
DeVries, Huco, The mutation theory. 2 vols. 1909-1910; Species and varieties, 
their origin by mutation, 2d ed., 1906; Die Mutationen in der Erblichkeitslehre. pp. 42- 
Berlin. 1912; The principles of the theory of mutation. Science 40:77-84. 1914. 
? Wits, J. C., Some evidence against the theory of the origin of species by natural 
selection of Seite + variations, and in favor of origin by mutation. Ann. Roy. 
Bot. Gard. Peradeniya 4:1-15. 1907. 
