HEREDITY OF ACQUIRED CHARACTERS 193 



The second is that none of the six or seven " mutantes " of 

 M. Vries ever occurred wild ; but resulted from their being 

 cultivated under the artificial conditions of a garden. Such has, 

 of course, been the case with all cultivated races of flowers, 

 fruits and vegetables. 



Hence, their characters were in all cases "acquired" in 

 response to the direct action of the environment ; and as M. 

 H. de Vries proved, the acquired characters reappeared from 

 the first generation onwards, and so proved themselves to be 

 hereditary. 



The idea that " the reproductive organs cannot be affected " 

 is at once disproved by the acquired characters reappearing in 

 the seedlings. 



I had much talk with the late Prof. Sickenberger, of the 

 School of Medicine, Cairo, when in Egypt some years ago ; 

 and he was good enough to give me the following information : 

 " I have read with great interest your publication on Dr. 

 Weismann's theory, and I am very glad to see that your con- 

 clusions are entirely in accordance with my own observations. 

 I believe, if Weismann had had more special knowledge of 

 botanical matters he would not have undertaken to apply 

 his theory to plants. You have completely refuted ^ by your 

 explanations his assertion that a continuity of germ-plasm 

 exists in a certain series of somatic cells only. I cannot admit 

 any essential difference of characters between species and 

 varieties. Such being only due to greater or less degree of 

 qualities acquired by the influence of external conditions in 

 a longer or shorter time. Hybridisation comes in, in a second- 

 ary way, mixing those acquired qualities with another series. 

 Hereditary persistency is, I believe, nothing else than the 

 maintenance of those acquired qualities under the power of 

 inertia (gesetz der Tragheit). The more any acquired qualities 

 have changed the anatomical and chemical constitution of a 

 plant, so much the more will those qualities be persistent. If 



1 " Dr. Weismann's Theory of Heredity applied tO Plants," Natural 

 Science, vol, i., p. 171, 1882. 



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