hypothesis. They show that there is none of the alleged independence of the reproductive cells, but that the two sets of cells are in close communion. They prove that while the reproductive cells multiply and arrange themselves during the evolution of the embryo, some of their germ-plasm passes into the mass of somatic cells constituting the parental body, and becomes a permanent component of it. Further, they necessitate the inference that this introduced germ-plasm, everywhere diffused, is some of it included in the reproductive cells subsequently formed. And if we thus get a demonstration that the somewhat different units of a foreign germ-plasm permeating the organism, permeate also the subsequently formed reproductive cells, and affect the structures of the individuals arising from them, the implication is that the like happens with those native units which have been made somewhat different by modified functions: there must be a tendency to inheritance of acquired characters" (pp. 38–9).
The above passage is somewhat obscure. Its meaning, however, seems to be as follows:—Some of the germ-plasm of the first-formed reproductive cells passes into the somatic cells to the farthest limits of the organism. If then, any part of the organism acquires characters these are, by part of the germ-plasm there abiding, conveyed back to the germ cells subsequently formed, and thus acquired characters are transmitted. This Mr. Spencer thinks is proved by what he imagines is a fact, viz. that foreign germ-plasm is incorporated with the somatic cells, whence it enters reproductive cells subsequently formed, whereby the progeny of subsequent sires are infected with the characters of the first sire. If my interpretation is correct, it must be admitted that Mr. Spencer has here built a very pretty superstructure on remarkably slight foundations.
Professor Romanes (Contemporary Review, April 1894)
