Following the lead of other evolutionists, Wasmann has striven to saddle fixism with the fatuity of periodic catastrophism and “creation on the installment plan.” But even Cuvier, who is credited with having originated the theory of catastrophism, did not go to the absurd extreme of hypothecating reiterated creations, but sought to explain the repopulation of the earth after each catastrophe by means of migrations from distant regions unaffected by the catastrophe. Historically, too, fixism has had its uniformitarian, as well as its catastrophic, versions. In fact, Huxley classifies both uniformitarianism and catastrophism as fixistic systems, when he says: “I find three more or less contradictory systems of geologic thought ... standing side by side in Britain. I shall call one of them Catastrophism, another Uniformitarianism, the third Evolutionism.” (“Lay Sermons,” p. 229.) Obviously, then, fixism is separable from the hypothesis of repeated catastrophes alternating with repeated “creations.” Stated in proper terms, it is at one with evolutionism in rejecting as undemonstrated and improbable the postulate of reiterated cataclysms. It freely acknowledges that, in the absence of positive evidence of their occurrence, the presumption is against extraordinary events, like wholesale catastrophes. It sanctions the uniformitarian tenet that ordinary cosmic processes are to be preferred to exceptional ones as a basis of geological explanation, and it repudiates as unscientific any recourse to the unusual or the miraculous in accounting for natural phenomena. Its sole point of disagreement with evolutionism is its refusal to admit organic changes of _specific_ magnitude. It does, however, admit germinal changes of _varietal_ magnitude. It also recognizes that the external characters of the phenotype are the joint product of germinal factors and environmental stimuli, and admits, in consequence, the possibility of purely _somatic changes_ of considerable profundity being induced by widespread and persistent alterations in environmental conditions. Like Darwin, the uniformitarian fixist ascribes the origination of organic life to a single vivifying act on the part of the Creator, an act, however, that was _formative_ rather than _creative_, because the primal forms of life, whether few or many, were all evolved through Divine influence from preëxistent inorganic matter. Unlike Darwin, he ascribes the continuation of organic life to generative processes that were univocal (_generationes univocae_), and not gradually-equivocal (_generationes paulatim aequivocae_). In the next chapter, we shall see that, in attributing the initial formation of species to a Divine act, neither Darwin nor the creationists exposed themselves to the charge of explaining the “natural” by means of the “miraculous.” And, as for the process by which living forms were continued upon earth, the univocal reproductive process upheld by fixism is more manifestly a natural