Bateson on Variation 
' As long ago as 1894 Bateson published his 
Materials for the Study of Varzatzon, in which 
he set forth a large number of cases of discon- 
tinuous variation which he had collected. He 
pointed out that species are discontinuous, that 
they are sharply separated one from another, 
whereas ‘“‘environments often shade into one 
another and form a continuous series.” How, 
then, he asked, if variations are minute and con- 
tinuous, have these discontinuous species arisen? 
May not variation prove to be discontinuous, and 
thus make it clear why species are discontinuous? 
On page 15 of the above-cited work we find: 
“The preliminary question, then, of the degree 
of continuity with which the process of evolution 
occurs has never been decided. In the absence 
of such a decision, there has nevertheless been a 
common assumption, either tacit or expressed, 
that the process is a continuous one. The 
immense consequence of a knowledge of the 
truth as to this will appear from a consideration 
of the gratuitous difficulties which have been 
introduced by this assumption. Chief among 
these is the difficulty which has been raised in 
connection with the building up of new organs 
in their initial and imperfect stages, the mode of 
transformation of organs, and, generally, the 
selection and perpetuation of minute variations. 
Assuming, then, that variations are minute, we 
are met by this familiar difficulty. We know 
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