HEREDITY OF ACQUIRED CHARACTERS CUENOT. 339 



of view of evolution. Many experiments have been made with the 

 primary factors, as Giard calls them. Hundreds of experiments, 

 bearing especially on insects, have given negative results as far as 

 the heredity of acquired characters was concerned. A few only 

 (Standfuss, E. Fischer, Schroder) have had a feebly positive result. 

 But these are not sufficiently convincing, the authors having worked 

 with species naturally so variable that it has been necessary to ask 

 ourselves whether the characters which they believed to be acquired 

 did not exist in a latent state in certain individuals before the modifi- 

 cation of the medium. The experiments of Kammerer are still more 

 puzzling. From 1904 to 1911 he published a great number of re- 

 searches demonstrating the considerable influence of the environment 

 on the methods of reproduction of amphibians {Alytes obstetricans, 

 Salamandra maculosa and atra), on the color of amphibians {Sala- 

 mandra maculosa) and of reptiles (Lacerta) , and bringing into evi- 

 dence in the majority of cases the transmission of acquired charac- 

 ters. It is not too much to say that at first glance the results of 

 Kammerer appear incredible. He certainly had at his disposal an 

 exceptional installation at the Prater in Vienna (BiologischeVersuchs- 

 anstalt der Akademie der Wissenschaften), but that he should have 

 been able to accomplish even with these means breedings of such 

 great difficulty and of such long duration is indeed surprising. From 

 the very beginning his experiments seemed too successful, too 

 demonstrative, and too extraordinary to merit confidence. Boulenger 

 and Bateson 5 have criticized them severely, and there have even been 

 mentioned trickeries and substitutions of preparations. Hans 

 Przibram, who also worked at the Prater, has been kind enough to 

 tell me that nothing of this sort took place, but the suspicion is at 

 least an indication that Kammerer's results have met with a general 

 incredulity. Argument can not then be based on them until they 

 have been confirmed by observers in other countries, something which 

 has not yet occurred — in fact, quite the contrary. 



I limit myself to this preamble, not intending to criticize one by one 

 the various facts presented in botany or in zoology as proofs of the 

 heredity of acquired characters. There are many of them, but they 

 have not withstood criticism since none of them carry conviction. 6 



Quite recently the question has taken on a new aspect with the very 

 remarkable work of F. Guyer and E. A. Smith. 7 It is known that 



5 Bateson, Problems of Genetics, 2d edition, New Haven, 1916, pp. 199-211. Boulen- 

 ger, Experiments on color-changes of the spotted salamander, etc. Proc. Zool. Soc. 

 London, 1921, p. 99. 



« See Weismann, Essais sur l'He're'dite, 1892, and Vortrage tiber Descendenztheorie, 

 Jena, 1902 ; Bateson, Problems of Genetics, 1916 ; Cuenot, La genese des especes ani- 

 mates, 2d edit., Alcan, Paris, 1921. 



7 Guyer and Smith, Studies on cytolysins. II. Transmission of induced eye-defects, 

 Journ. Exp. Zool., vol. XXXI, 1920, p. 171. Guyer, Immune sera and certain biological 

 problems, Amer. Natur., vol. LV, 1921, p. 97. 



