Temporary Heredity and the Mechanism of Adaptation

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Abstract
Experiments show that selection for resistance or susceptibility to specific bacterial strains by testing each generation''s reaction to this bacterial strain after the next generation has been born and weaned has not led to any marked progressive change in resistance. On the other hand selection by inoculating each generation before the next one is born and breeding from the survivors leads to a marked progressive increase of resistance. This suggests that there is an hereditary factor involved in this increase of resistance. Evidence is submitted that acquired immunity is always only temporary as regards the actual presence of antibodies but the stimulus of invasion by a strain of bacteria leaves the organism attuned to that stimulus, and if the same strain should invade the host again the latter responds more quickly and efficiently than it did to the first invasion. The attunement to the stimulus therefore is more permanent than the presence of the antibodies and it can apparently be inherited in a temporary manner. It both appears and fades gradually and not suddenly as in mutations. This suggests that all adaptive acquired characters are only temporary even in the lifetime of the individual in which they arise, but by acquiring them the organism became attuned to an environmental stimulus and this attunement is inherited. Adaptive features therefore arise earlier and with greater ease in successive generations if the environment remains the same. Evidence in support of this is drawn from many fields. Acquired characters are rarely if ever directly inherited.