104 REPORT OF THE CONFERENCE ON GENETICS. 
not at all be confounded with heredity) has not been observed with any 
degree of certainty in my experiments. Small plants gave a less number 
of seeds—that was all. I hope to be successful in finding such action 
of selection in pure monomodal lines—in being able to demonstrate the 
difference between such secondary effect and a veritable type-alteration. 
It may be that such ‘‘spurious’’ type-alterations are more frequently 
to be found in breeding experiments with animals. I never heard about 
them; but they perhaps may have been present in some of De Vries’ (11) 
cases of selection experiments combined with over-nutrition. Unfortu- 
nately De Vries’ materials have not been homogeneous in my sense of 
the word. 
As to the conception of Galton’s (12) law of filial regression, Pearson (13) 
has the merit of taking in the clearest manner the consequences of that law 
when he maintains that continued selection is not checked by regression, 
and must therefore produce an alteration of the type (“Grammar of 
Science,” p. 483). Nevertheless we meet quite erroneous conceptions as 
to the significance of the above-mentioned Galton’s law, so—to take one 
example only—in the recent book of Lotsy (14), who gives an exposition 
of these matters without understanding their bearings. It is of course 
another matter that the often-mentioned law is not a biological law at all, 
but only the statistical expression of the compound character of the 
population. 
Still more confusion is found as to the celebrated question whether 
the ambient conditions may be able to produce transmissible alterations 
in the characters of organisms—.e. whether exterior conditions may be 
able to produce an alteration of types. We see here, in place of sober 
experiments, speculations of a very audacious nature, mostly based upon 
the confusion of individual adaptative reactions with a supposed alteration 
of the veritable types (qualities of gametes and zygotes). Most of the 
‘“ Neo-Lamarckian ” literature demonstrates the necessity of exact 
experiments in all these matters. 
It is a pleasure to emphasise the exact experiments of EH. Chr. Hansen 
with yeast-cells (15), cultivated in different ways. Mr. Hansen has operated 
with ‘pure lines’’; his celebrated studies in fermentations were founded, 
as is well known, in an exact analysis of yeast-populations—just the same 
principle that Vilmorin introduced into his heredity experiments more 
than fifty years ago, the principle which has also been followed in Svalof 
and in my own researches. 
The influence of the ambient conditions upon the types of organisms 
can only be studied in reality by means of “pure lines’’—if we are to 
have some warrant as to the meaning of the results: the presumed type- 
alteration may be nothing but the effect of an unconscious selection in 
impure, mixed populations. But even in pure lines we have the possibility 
of mutation, and perhaps extreme conditions may be able to set mutability 
in action. The whole theory of type-altering by means of altered con- 
ditions and direct adaptation is still so vague and floating that it seems 
unjustifiable to teach it as a sort of semi-scientific creed. As to the 
evidence from observations in Nature, I cannot omit the striking remarks 
of Bateson (16), that the differences in ambient nature are gradual, but 
the differences in crganisms from the same locality are specific. 
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