No. 581] 



GERM CELLS AND SOMATIC CELLS 



hirudin, and that those having received preliminary in- 

 jections of hirudin would also be immune against colloidal 

 copper. We wished to test this conclusion and undertook 

 therefore experiments in which we immunized animals 

 with one substance and examined later their immunity 

 not only against the substance with which they were 

 immunized, but also against the other substance. These 

 experiments showed that animals immunized with col- 

 loidal copper are essentially only immune against the 

 effect of colloidal copper, not of hirudin, and those immu- 

 nized with hirudin are immune against hirudin, but not 

 noticeably (very weakly, if at all) against colloidal copper. 

 The acquired immunity is therefore a specific one. This 

 specificity can be shown to exist if after preliminary in- 

 jections given from the second to the fifth day after inocu- 

 lation the immunity is tested through cross injections 

 given from the ninth to the thirteenth day. It can also 

 be demonstrated in the tumors transplanted into other 

 animals after preliminary injections in the first set of 

 animals. The specificity concerns therefore the immunity 

 which is produced in the tumor cells and probably also the 

 immunity in the organism of the injected animals. These 

 investigations prove then (1) that an acquired immunity 

 against the injurious action of certain substances can be 

 localized in the cells concerned; (2) that this immunity 

 can be transferred to later cell generations; and (3) that 

 although the effect of two substances on the cells is appar- 

 ently the same, the mechanism through which this effect 

 is produced differs in the case of each substance, and that 

 therefore the immunity produced against the injurious 

 action of these substances is a specific one for the sub- 

 stances injected. We see therefore that in a similar 

 manner as in germ cells an effect produced through an 



a transmission of changes produced through an external 

 (chemical) agenev may be transmitted to later genera- 

 tions also in the case of somatic cells. But the further 

 results we obtained in the case of somatic cells suggest the 

 question whether the lesion produced and transmitted 



