156 THE THEORY OF MUTATION 
to the influence of the environment upon the larval 
stages of the beetle are not inherited ; but if the female 
is subjected to abnormal conditions for a few days at 
the time when the eggs are maturing, the eggs and 
larve being afterwards allowed to develop in the 
normal environment, a greatly increased number of 
mutations is obtained, the majority of which are the 
same as those found much more rarely in Nature. 
MacDougal, too, has met with some success in the 
attempt to produce mutations artificially in plants. 
In one or two cases, after injecting weak solutions of 
different chemical substances into the young ovaries 
of Raimannia and (Enothera, seedlings were obtained 
which differed from anything previously seen. Up to 
the present time these successes seem to be too few in 
number to allow of any definite conclusions being based 
upon them. 
Blaringhem has also recently published observations 
which seem to show that in the maize-plant injuries to 
the parent occurring previously to the differentiation 
of the germ cells may lead to permanent modifications 
in the offspring. In neither of these three sets of 
experiments did the modification produced in the off- 
spring show any trace of an adaptive relation to the 
exciting cause which operated upon the parent. 
So much may be stated in order to indicate the 
direction in which research is proceeding. In the 
course of another decade we may reasonably hope to 
find out something more about the natural and artificial 
production of mutations. 
