850 



PROVISIONAL HYPOTHESIS 



Chap. XXVIL 



until a better one be advanced, it will serve to bring together 

 a multitude of facts which are at present left disconnected by 

 any efficient cause. As Whewell, the historian of the inductive 

 sciences, remarks : — " Hypotheses may often be of service to 

 *' science, when they involve a certain portion of incomplete- 

 " ness, and even of error." Under this point of view I venture 

 to advance the hypothesis of Pangenesis, which implies that 

 every separate part of the whole organisation reproduces 

 itself. So that OAmles, spermatozoa, and pollen-grains, — the 

 fertilised egg or seed, as well as buds, — include and consist of 

 a multitude of germs thrown off from each separate part or 

 unit.^ 



In the First Part I will enumerate as briefly as I can the 

 groups of facts which seem to demand connection ; but certain 



' This hypothesis has been severely 

 criticised by many writers, and it 

 will be fair to give references to the 

 more important articles. The best 

 essay which I have seen is by Prof. 

 Delpino, entitled 'Sulla Darwiniana 

 Teoria della Pangenesi, 1869,' of 

 which a translation appeared in 

 'Scientific Opinion,' Sept. 29, 18(39 

 and the succeeding numbers. He 

 rejects the hypothesis, but criticises 

 it fairly, and I have found his criti- 

 cisms very useful. Mr. Mivart 

 (•Genesis of Species,' 1871, chap, x.) 

 follows Delpino, but adds no new 

 objections of any weight. Dr. Bastiaa 

 (' The Beginnings of Life,' 1872, vol. ii. 

 p. 98) says that the hypothesis " looks 

 " like a relic of the old rather than a 

 " fitting appanage of the new evolu- 

 " tion philosophy." He shows that I 

 ought not to have used the term 

 ♦' pangenesis," as it had been previously 

 used by Dr. Gros in another sense. 

 Dr. Lionel Beale ('Nature,' May 11, 

 1871, p. 26) sneers at the whole doc- 

 trine with much acerbity and some 

 justice. Prof. Wigand (' Schrifteu der 

 Gesell. der gesammt. Naturwissen. zu 

 Marburg,' Bd. ix., 1870) considers the 

 hypothesis as unscientific and worth- 

 less. Mr. G. H, Lewes (' Fortnightly 

 Review,' Nov. 1, 1868, p. 503) seems 

 to consider that it may be useful : he 



makes many good criticisms in a per- 

 fectly fair spirit. Mr. F. Galton, after 

 describing his valuable experiments 

 (' Proc. Royal Soc' vol. xix. p. 393) on 

 the intertransfusion of the blood of 

 distinct varieties of the rabbit, con- 

 cludes by saying that in his opinion 

 the results negative beyond all doubt 

 the doctrine of Pangenesis. He in- 

 forms me that subsequently to the 

 publication of his paper he continued 

 his experiments on a still larger scale 

 for two more generations, without 

 any sign of mongrelism showing itself 

 in the very numerous offspring. I 

 certainly should have expected that 

 gemmules would have been present in 

 the blood, but this is no necessary 

 part of the hypothesis, which mani- 

 festly applies to plants and the lowest 

 animals. Mr. Galton, in a letter to 

 ' Nature '(April 27, 1871, p. 502), also 

 criticises various incorrect expressions 

 used by me. On the other hand, 

 several writers have spoken favour- 

 ably of the hypothesis, but there 

 would be no use in giving references 

 to their articles. 1 may, however, 

 refer to Dr. Ross* work, 'The Graft 

 Theory of Disease ; being an applica- 

 cation of Mr. Darwin's hypothesis of 

 Pangenesis,' 1872, as he gives several 

 original and ingenious discussions. 



