ENVIRONMENT AND EVOLUTION KROPOTKIN. 415 



contention that no material influences can be transmitted from the 

 protoplasm of a cell to the germ plasm of its nucleus, distinctly con- 

 tradicted it. 1 



More than that. The fundamental point of all the hypotheses 

 brought forward by Weismann was the isolation of the germ plasm 

 and the impossibility of its being influenced by the changes going on 

 in the body under the influence of the outer agencies. But the more 

 we advanced in the study of heredity the more we were brought to 

 realize the close interdependence of all the organs and tissues of the 

 living beings — plants and animals alike — and the impossibility of 

 one of their organs being affected without a disturbance being pro- 

 duced in all parts of the organism. 2 We learned from the best 

 embryologists that the living substance which is the bearer of in- 

 heritance is not localized in the nucleus of the germ cells, and that 

 an intercourse of substances between the nucleus and the cell plasm 

 must be taken as proved. 3 Finally, we have now experiments tend- 

 ing to prove that even unimportant lesions of the body may be fol- 

 lowed by important modifications in the reproductive cells. 4 



The difficulties which the hypothesis too hastily framed by Weis- 

 mann had to contend with when it was confronted with the scientific 

 observation of nature, and the new hypotheses he brought forward 

 to meet the rapidly accumulated contradictory facts, were xliscussed 

 in my above-mentioned article. Sufficient to say here that, after 

 having emphatically denied at the outset that his " immortal " germ 

 plasm could be influenced by external agencies " in the same direction 

 as that taken b}^ the somatogenic changes (in the body) which fol- 

 low the same causes " ; 5 and after having maintained that the mix- 

 ture of two germ plasms in sexual reproduction (that is, amphi- 

 mixis) was " the only way " that hereditary influences " could arise 



1 Oscar Hertwig, Der Kampf urn Kernfragen der Entwickelungs- and Vererbungslehre, 

 Jena, 1909, pp. 44-45 and 107-108. See also Nineteenth Century, March, 1912, p. 520. 



2 To a review of this question in his capital work, heredity (London, 1908, p. G4), 

 Prof. J. Arthur Thomson added the following words : " Holding firmly to the view which 

 we have elsewhere expressed, that life is a function of interrelations, we confess to hesita- 

 tion in accepting without saving clauses any attempt to call this or that part of the 

 germinal matter the exclusive vehicle of the hereditary qualities." 



3 Rabl, Ueber Organ-bildende Substanzen und ihre Bedeutung fur die Vererbung : E. 

 Godlewski jun., in Roux's Archiv, vol. xxviii, 1908, pp. 278-378. The connection between 

 all the cells in plants has been proved by observation, and now it begins to be proved for 

 animals. The lively intercourse between the cells of the animal's body by means, of the 

 wandering cells, which was observed during regeneration processes, seems not to be 

 limited to these processes. The researches of His, Kupffer, Loeb, Roux, and Herbst are 

 tending to prove that the same cells also take part in the ontogenetic processes. (See 

 the articles of Herbst in Biologisches Centralblatt, vols, xiv and xv.) As to Nussbaum. 

 Whose work suggested to Weismann the " continuity " of the germ-plasm, his idea is that 

 the germ cells are exposed to the same modifying agencies as the body cells (Archiv fur 

 niikroscopische Anatomie, xviii, 1908, quoted by Prof. Rignano in La transmissibilit£ des 

 caracteres acquis, p. 1G9.) Many other biologists come to the same conclusion. 



4 Experiments of Ignaz Schiller on Cyclops and tadpoles ; preliminary report in Roux's 

 Archiv, xxxiv, pt. 3, pp. 469-470. 



6 Essays, ii, 190. 



