the rest of it. So far from it being true that in the lower animal world acquired traits are not transmissible, it is precisely there, in the lowest, that they are distinctly transmissible. In that stratum of life which, in our imperfect knowledge, we at present regard as the lowest, where the plant and animal kingdoms merge, and whence both have arisen, every organism being unicellular is a germ cell, which, besides being extremely minute and relatively simple, is one on which external conditions act directly, whereby the constitution of the cell is so modified that a like variation is produced in the next generation. For this reason, as already indicated, bacteriologists, by means of their "attenuated cultures," are able to deeply modify the characteristics of microbic organisms. As regards higher animals, the high multicellular animals with which alone Mr. Spencer deals in his paper, nothing that he has said, and nothing that any one else has said, establishes a shadow of proof that in them acquired traits are transmissible—that the changes, which the action of the environment produces in their somatic cells, so affect their germ cells, that these latter, when they proliferate, reproduce in the new organism variations like to those which the action of the environment produced in the parent.
