264 HEREDITY AND DISEASE 



a general way poison or weaken the germ-cells along with the 

 whole body, or that in the case of a mammalian mother the 

 foetus may be poisoned or weakened through the placental 

 circulation. 



It must be noted, however, that many medical authorities 

 do not in the least agree with the position which we have stated. 

 Thus Mr. Jonathan Hutchinson says : " Without venturing to 

 do more than mention the Weismann logomachy, which has 

 recently disturbed the creeds of some biologists, I wiU take 

 permission to avow my belief that with the sperm and germ 

 supplied by parents there may pass to the offspring tendencies 

 to the reproduction of all that these parents had acquired up 

 to the date of the sexual congress. By the term ' acquired ' 

 is meant all that has been received by modification of vital 

 processes, not what has been imposed or taken away by external 

 violence." We must refer to the chapter on the transmissibility 

 of acquired characters for our answer to this opinion. 



Experimental Evidence. — It is sometimes said that the famous 

 experiments of Brown-Sequard showed conclusively that artificially- 

 induced " guinea-pig epilepsy " is transmissible. But a scrutiny 

 of the case, such as we have given in the previous chapter, leaves 

 us reluctant to base an argument on Brown-Sequard's results. 



The only other cases which seem relevant are those which have 

 to do with artificially induced immunity. By injections of serum 

 and the like — the details do not concern us — it is possible to render 

 an organism immune, e.g. to diphtheria. Are the offspring thereby 

 rendered hereditarily immune ? No case is known where the 

 offspring of an immunised father showed any " anti-bodies " in 

 the blood or any hint of immunity. There is no convincing evidence 

 of transmission of immunity from the male parent. 



It is known, however, that the offspring of an artificially im- 

 munised mammalian mother (guinea-pig, rabbit, etc.) may exhibit 

 immunity. But this probably means that the " anti-bodies," 

 agglutinins, precipitins, or whatever they may be called, passed 

 via the placenta from the maternal to the foetal blood. But this 

 has nothing to do with inheritance. 



