974 
life, a view which thus persisted and is still 
generally held. 
Subsequently, both Darwin and Wallace 
admitted progressive variation without 
natural selection, which was considered to 
be but one of several factors contributing 
to evolution. The original statement, how- 
ever, continues to represent Darwinism in 
the scientific world, and, as has been well 
said,* ‘ The biologist of to-day is more Dar- 
winian than Darwin, and explains on the 
Darwinian hypothesis even those cases 
which had presented difficulties to Darwin’s 
own mind.” This tendency signifies that 
the inadequacy of all other explanations 
-has become more and more thoroughly 
realized, thus causing a return to Darwin 
as the author of the only real contribution 
to the study of biological causes. The 
static or selective theory of evolution has, 
however, attained its present popularity, 
not because it has been shown to have any 
universal application in nature, but because 
it has remained the only suggested explana- 
tion which seemed to be supported by 
definite and particularized phenomena. 
VARIATION AND CONJUGATION AS KINETIC 
PHENOMENA. 
It is probable that in the study of bio- 
logical motion it will be found desirable to 
distinguish at least four types of variation 
or kinds of differences between closely re- 
lated organisms. Some modifications may 
be described as mere chemical or physical 
reactions to definite substances, forces or 
conditions; + some are more clearly patho- 
* Hayeraft, ‘ Darwinism and Race Progress,’ Lon- 
don, 1900, 28. 
+ According to Professor Osborne; ‘‘ When the pale 
Proteus is taken from the Austrian caves, placed in 
the sunlight, and in the course of a month becomes 
darkly pigmented, there are two interpretations of 
this pigmentation; either that we have revived a 
latent character, or that we have created a new char- 
acter.’’ American Naturalist, May, 1899, p. 431. It 
would seem, however, that this experiment may prove 
SCIENCE. 
[N. 8. Vou. XIII. No. 338. 
logical and are the result of inherent weak- 
ness or derangement of the organism ; while 
others are normal vibrations or fluctuations 
of form, size, color or other characteristics 
having, perhaps, no very definite single 
cause, nor any pronounced tendency to 
repeat themselves. Essentially different, 
though often confused with one or the 
other of the above, are the peculiarities 
which represent lines of change or diver- 
gence, upon which the organic series if un- 
hindered may proceed with no diminution, 
but rather with an increase of structural and 
physiological efficiency, and often with per- 
sistence and rapidity. To this class belong 
the ‘sports’ which come true to seed and 
yet show no signs of debility, and which, 
though crossed with the parental type, im- 
press their characters upon a large majority 
of the offspring. In other words, varia- 
tions of this kind are prepotent because 
they open avenues of advance and adjust- 
ment welcome to the organism and neces- 
sary to the maintenance of the efficiency of 
protoplasmic structure and function. 
Variation and conjugation may thus 
be supposed to minister to the same re- 
quirement of the protoplasmic organiza- 
tion. There is little or no warrant for the 
current belief that variation and heredity 
are phenomena essentially connected with 
sexual reproduction, and thus explainable 
through a knowledge of the structure and 
mechanism of conjugating cells. In final 
analysis reproduction is not a sexual but a 
vegetative process. Because in some groups 
the conjugation of nuclei is an indispen- 
sable preliminary to reproduction,* the most 
neither of these alternatives, but merely that the skin 
of Proteus is capable of the photic reaction which gen- 
erally influences the formation of pigment. 
*SoIENCE, N. S., 1900, XIIL., pp. 940-946. In this 
presentation of Professor Hertwig’s views the issue is 
still obscured by a residue of the former terminology. 
Thus on page 943 we read that ‘‘ the sexual reproduc- 
tion of Metazoa is a continuation of the method of 
reproduction in the Protozoa, while the budding and 
