tissues of the parent are constituted: units composed, as we must assume, of variously-arranged molecules of protein. So that the big thing may pass, and the little thing may pass, but the intermediate thing may not pass" (p. 32).
It is hardly necessary to argue the matter: of course if the gemmules or physiological units exist they must be able to enter the germ cells as do food molecules, as do microbes, and as do spermatozoa. This is not the thing denied. It is the very existence of the elements which cause the germ cells to proliferate into organisms with the acquired variations of the parent that is denied. The existence of gemmules or physiological units is assumed, that the transmission of acquired variations may be accounted for. There is no other evidence of their existence, except such as is furnished by the supposed transmission of such variations. But as I have just shown, acquired variations as regards higher animal organisms, to which alone Mr. Spencer directs his attention, are apparently not transmitted, but that only the power to vary in response to stimulation is transmitted; and variations in this power cannot be acquired in the sense that is increased by stimulation, by use, and decreased by the lack of it, by disuse. Therefore neither acquired variations nor an acquired power of varying can be transmitted; and therefore since there is nothing to show that gemmules or physiological units exist, it is vain until this is proved to discuss the possibility of their entrance into the germ cells. That is not, as I say, the point at issue.
But Mr. Spencer has another string to his bow. According to him, and in this he follows Mr. Adam Sedgwick, a so-called multicellular organism is not really a multicellular organism, but "a continuous mass of vacuolated protoplasm," a sort of gigantic unicellular organism.
