VII.] TRANSMISSION OF ACQUIRED CHARACTERS. 42^ 



plants produced from 1884-1886 fifty-three single flowers and 

 no double ones.' 



In the converse experiment XIX, 'The seeds of single 

 flowers from different stocks were sown in pots, and the re- 

 sulting plants produced in 1885 and 1886 forty-tlircc flowers, 

 of which all were typical except one'; while plants produced 

 in the garden by seed from the same sources, yielded 166 single 

 and five double flowers. Hoffmann also describes other ex- 

 periments in which the seeds from double flowers produced 

 plants vi^hich also yielded many double flowers. Thus, for 

 example, in experiment XXI seeds yielded by the d(juble 

 flowers oi Papaver alpimtm were sown in the garden and pro- 

 duced numerous plants, which in 1885 and 1886 bore 284 single 

 and twenty-one double flowers, that is 7 per cent, of the latter. 



It will therefore be seen that the transmission of the abnor- 

 mality is by no means proved beyond the possibility of doubt, 

 for who can decide between the effects due to heredity and 

 changed conditions in the last experiment? I have no doubt 

 however that the results are at any rate in part due to the 

 operation of heredity, for I do not see how the phenomena can 

 be otherwise understood. Nevertheless I cannot admit the 

 transmission of acquired characters on this evidence, for the 

 changes which have appeared are not 'acquired' in the sense 

 in which I use the term and in the sense required by the general 

 theory of evolution. It is true that they may be described by 

 the use of this word; inasmuch as they are characters which 

 the plant has come to possess : we are not however engaged in 

 a mere dispute about terms, but in the discussion of a weighty 

 scientific question. Our object is to decide whether changes in 

 the soma (the body, as opposed to the germ-cells) whicli have 

 been produced by the direct action of external influences, in- 

 cluding use and disuse, can be transmitted ; whether they can 

 influence the germ-cells in such a manner that the latter will 

 cause the spontaneous appearance of corresponding changes 

 in the next generation. This is the question which demands 

 an answ^er; and, as has been shown above, such an answer 

 v^^ould decide whether the Lamarckian principle of transforma- 

 tion must be retained or abandoned. 



I have never doubted about the transmission of changes 

 which depend upon an alteration in the germ-plasm of the re- 



