KANT AND EVOLUTION 41 



principle or presumption of science which must be adhered to at any 

 cost, namely: 



that throughout organic nature, amid all changes of individual creatures, the 

 species maintain themselves unaltered (die Species derselben sich unveriindert 

 erhalten) — according to the formula of the schools, quaelibet natura est con- 

 servatrix sui. Now it is clear that if some magical power of the imagination, 

 or the artifice of men, were capable of modifying in the bodies of animals the 

 reproductive faculty itself, of transforming Nature's original model or of 

 making additions to it, which changes should then become permanent in sub- 

 sequent generations, we should no longer know from what original Nature had 

 begun, nor how far the alteration of that original may proceed, nor — since man's 

 imagination knows no bounds — into what grotesqueries of form species might 

 eventually be transmogrified {in welche Fratzengestalt die Gattungen und Arten 

 zuletzt noch verioildern diirften) . In view of this consideration, I for my part 

 adopt it as a fundamental principle to recognize no power in the imagination 

 to meddle with the reproductive work of Nature, and no possibility that men, 

 through external, artificial modifications, should effect changes in the ancient 

 original of a species in any such way as to implant those changes in the repro- 

 ductive process and make them hereditary. For if I admit a single instance of 

 this sort, it is as if I admitted the truth of a single ghost-story or tale of magic. 

 The boundaries of reason are then once for all broken through, and errors rush 

 in by thousands through that opening. There is, meanwhile, no danger that, in 

 adopting this conclusion, I may take a position of blind or stubborn incredulity 

 towards real facts of experience. For all these romantic (abenteuerlich) occur- 

 rences have without exception one peculiarity, namely, that they can not be 

 subjected to experiment, but are supposed to be proved merely by casual observa- 

 tions. But whatever, though capable, indeed, of experimental testing, offers no 

 experimental evidence, or employs all sorts of excuses to avoid such a test, is 

 mere fiction and illusion. 31 



Nothing could better exhibit Kant's characteristic state of mind on 

 biological questions than this passage. There are occasional bits of 

 sound sense in it and of discriminating judgment about scientific 

 method; and there is a certain power of at least seeing where the signifi- 

 cant problems lie. Yet, though he had come under the influence of 

 evolutionistic conceptions, and is in these very writings endeavoring to 

 apply genetic methods to certain biological inquiries, he recoils in 

 horror before the idea of admitting that real species are capable of 



28 The " Physical Geography " is equally emphatic in repudiating both in- 

 heritance of acquired characters and mutation of species: "External things 

 may, indeed, provide the occasions, but they can not be the efficient causes, of 

 the appearance of characters that are necessarily transmitted and inherited. 

 As little as chance or physico-mechanical causes can bring an organic body into 

 existence, just so little can they imprint anything upon the reproductive fac- 

 ulty, that is, produce any effect that is itself reproduced, either as a special 

 form or as a relation of the parts. Air, light and nutrition can modify the 

 growth of an animal body, but they can not furnish this change with a power 

 of reproducing itself after its original causes are no longer operative. . . . For 

 it is not possible that anything should so penetrate into the reproductive faculty 

 as to be capable of gradually removing the creature from its original determina- 

 tion and bringing about a real and self-perpetuating departure from the specific 

 type {Ausartung). 



