410 ON THE SUPPOSED BOTANICAL PROOFS OF THE 



In the converse experiment XIX. ' The seeds of single flowers 

 from different stocks were sown in pots, and the resulting 1 plants 

 produced in 1885 and 1886 forty-three flowers, of which all wore 

 typical except one ; ' while plants produced in the garden by seed 

 from the same sources, yielded 166 single and five double flowers. 

 Hoffman also describes other experiments in which the seeds from 

 double flowers produced plants which also yielded many double 

 flowers. Thus, for example, in experiment XXI. seeds yielded by 

 the double flowers of Papaver alpinum were sown in the garden 

 and produced numerous plants, which in 1885 and 1886 bore 284 

 single and twenty-one double flowers, that is 7 P er cent, of the 

 latter. 



It will therefore be seen that the transmission of the abnormality 

 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 en- 

 gaged 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) 

 which have been produced by the direct action of external in- 

 fluences, including 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 

 answer ; and, as has been shown above, such an answer would decide 

 whether the Lamarckian principle of transformation 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 reproductive 

 cells, for I have always asserted that these changes, and these alone, 

 must be transmitted. If any one makes the contrarv assertion, 



