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THE AMEBIC AN NATURALIST [Vol. XLIX 



identical defects in the developing organisms. It seems 

 to be otherwise in the case of certain external conditions 

 which produce first changes in some somatic cells which 

 on their part apparently induce such secondary changes 

 in the germ cells that in the offspring, not exposed to the 

 external conditions that affected the parents, again 

 changes appear in some somatic cells similar to those 

 produced in the parents through the external conditions. 

 Such results were published by Kammerer. In the latter 

 case the changes produced and transmitted to the off- 

 spring showed evidently a characteristic specific relation- 

 ship to definite external conditions. Such a specific rela- 

 tionship is, as far as we can judge at present, lacking in 

 the case of defects or deficiencies produced through the 

 action of poisons. 



I wish to report briefly on a change which my collab- 

 orators Mover S. Fleisher, Miguel Vera and myself 15 have 

 produced in somatic cells, a change which is transferase to 

 the following cell generations and is therefore hereditary, 

 and which, while it would be pronounced non-specific, if 

 we should use ordinary criteria, can through the use of 

 special methods be shown to possess a definite, character- 

 istic relationship to the external factor that caused this 

 change and must therefore be called specific. The obser- 

 vations on which these conclusions are based are briefly 

 as follows: 



If we inoculate mice with the mouse carcinoma used by 

 us in our experiments and from the ninth to the fourteenth 

 day after inoculation give on successive days four intra- 

 venous injections of such substances as colloidal copper 

 or hirudin, a marked inhibition in growth takes place 

 during the period of injection. The intensity of this 

 inhibition varies in different cases and it is possible for 

 us by using a combination of two substances to cause a 

 retrogression of a considerable number of tumors. Now, 



is Moyer S. Fleisher and Leo Loeb, Jour. Exper. Med., Vol. XX, 1914, 

 p. 503. Moyer S. Fleisher, Miguel Vera and L»o Loeb, Jour. Exper. Med., 

 VoL XX, 1914, p. 522. Moyer S. Fleisher and Leo Loeb, Jour. Exper. Med., 

 Vol. XXI, 1915, p. 155. 



