424 ON SUPPOSED BOTANICAL PROOFS OF [VII. 



productive cells, for I have always asserted that these changes, 

 and these alone, must be transmitted. If any one makes the 

 contrary assertion, he merelj' proves that he does not understand 

 what I have said upon the subject. In what other way could 

 the transformation of species be produced, if changes in the 

 germ-plasm cannot be transmitted ? And how could the germ- 

 plasm be changed except by the operation of external influences, 

 using: the words in their widest sense ; unless indeed we assume 

 with Nageli, that changes occur from internal causes, and im- 

 agine that the phyletic development of the organic world was 

 planned in the molecular structure of the first and simplest 

 organism, so that all forms of life were compelled to arise from 

 it, in the course of time, and would have arisen under any con- 

 ditions of life. This is the outcome of Nageh's view, against 

 which I have contended for years. 



If we now use the term 'acquired characters' for changes in 

 the soma which, like spontaneous abnormalities, depend upon 

 previous changes in the germ-plasm, it is of course easy to prove 

 that acquired characters are transmitted ; but this is hardly the 

 way to advance science, for nothing but confusion would be 

 produced by such a use of terms ^ I am not aware that any 

 one has ever doubted that spontaneous characters, such as extra 

 fingers or toes, patches of grey hair, moles, &c., can be trans- 



* Compare a paper by J. Orth, ' Ueber die Entstehung und Vererbung 

 individueller Eigenschaften,' Leipzig, 1887. This author considers my 

 theory of the non-transmission of acquired characters to be incorrect, 

 because he will insist upon using the term ' acquired ' for those characters 

 which are due to spontaneous changes in the germ ; although he con- 

 siders that they are only indirectly acquired. He also reproaches me 

 with not having discriminated with sufticicnt clearness between the 

 two modes in which new characters are acquired by the body, and with 

 having altogether failed to take into account the class of characters 

 which are due to variations in the germ. On the very same page he 

 quotes the following sentence from my writings: — 'Every change of 

 the germ-plasm itself, however it may have arisen, must be transmitted 

 to the following generation by the continuity of the germ-plasm ; and 

 hence also any changes in the soma which arise from the germ-plasm 

 must be transmitted to the following generation.' Not only does the 

 transmission of Orth's ' indirectly acquired characters ' necessarily follow 

 from this sentence, but it is even distinctly asserted by it. I cannot 

 understand how any one who is aware of what happened at the meeting 

 of the Association of German naturalists at Strassburg in 1885, can charge 

 me with the confusion of ideas which has prevailed since Virchow 

 took part in the discussion of this question. 



