ARE ACQUIRED CHARACTERS HEREDITARY? 327 
Misunderstanding VI.—Transmission in unicellulars is not to the 
point.—It is not to the point to cite cases where unicellular organisms, 
such as bacteria or monads, have been profoundly and heritably modi- 
fied by artificial culture, so that, for instance, the descendants of a 
virulent microbe have been made to lose their evil potency. It is 
irrelevant because in regard to unicellular organisms we cannot draw 
the distinction between body and germinal matter, apart from which 
the concept of modifications is of no value. In artificial culture the 
whole character of the unicellular organism—its particular metabolism 
—is altered; it multiplies by dividing into two or more parts, which 
naturally retain the altered constitution. But this is worlds away 
from the supposed case of an alteration in the structure of the little toe 
so affecting the germ-cells that the offspring inherit a corresponding 
deformation. 
Professor L: Errera (1899) reported an experiment with a simple 
but multicellular mould (Aspergillus niger), which adapted itself to a 
medium more concentrated than the normal. The second generation 
of the mould was more adapted than the first, and the adaptation to 
the concentrated medium was not wholly lost after rearing in the nor- 
mal medium again. This looks like evidence of the inheritance of the 
acquired adaptive quality which was brought about as a direct modifi- 
cation. But the case does not really help us, since the distinction 
between soma and germ-plasm is not more than incipient in the mould 
in question. And even if the distinction were more marked, it would 
only show that the germ-plasm is capable of being affected along with 
the body, by a deeply saturating influence, which nobody has ever 
denied. 
Misunderstanding VII.—Changes in the germ-cells along with 
changes in the body are not relevant.—Another misunderstanding is due 
to a failure to appreciate the distinction between a change of the repro- 
ductive cells along with the body, and a change in the reproductive 
cells conditioned by and representative of a particular change in 
bodily structure. The supporters of the hypothesis that modifications 
may be transmitted point to the tragic cases where some poisoning of 
the parent’s system, by alcohol, opium, or some toxin, is followed by 
some deterioration in the offspring. There is no doubt as to the fact; 
the question is as to the correct interpretation. 
1. In some cases it may be that the whole system of the parent is 
poisoned—reproductive cells as well as body; the effect may be as 
direct on the germ-cells as on the nerve-cells. These, therefore, are not 
cases on which to test the transmissibility of an acquired character—i.e., 
