6. Vererbungslehre. t; 7; » 



the fact the latter recapitulate the development of the former — the law of 

 recapitulation musl be true because qo other method of development is con- 

 ceivable. Variations are either progressive or retrogressive; progressive if the 

 individual recapitulates the parental development with an additional step; 

 retrogressive if developmenl is abbreviated. Hence all retrogression is reversion. 

 All species tend to retrogress in the absence of natural selcction and the rate 

 of retrogression depends on that of previous progression. 



The eonclusions of the biometric school are attacked because they do 

 not take into account the m;i<s u( evidence familiär to every one of inberitance 

 in man. .Not seldom in biometric enquiries .... several scores or hundreds 

 of observers and thinkers are employed for years in ascertaining, with ;i mucb 

 lesser degree of certainty, that which a Single thinker may deduce in two 

 minntes from known and admitted truths*. And further many of the eonclusions 

 are wrong because they have not been tested by these admitted truths; e. g. 

 Pearson's eonclusions with regard to inberitance of mental characters are 

 invalid because similar results might have heen obtained from a record of the 

 kind of elothes worn by the children under investigation. 



The eonclusions of the Mendelian school are equally at fault. Dominance 

 and recessiveness are described as patency aud latency. ,There is no such 

 (hing as alternative inberitance; there is only alternative patency and latency'. 

 ,Unit segregation, gametic purity, and independent inberitance of characters 

 (in the Mendelian sense) are all myths that have been founded on experiment 

 but have not been tested . . .'. The apparent relation between Mendelian inberi- 

 tance and sex is explained by saying that Mendelian reproduetion is a variety 

 of sexual reproduetion, and Mendelian characters are essentially similar to se- 

 eondary sexual characters. The funetion of sex is to bring about retrogression, 

 so eliminating useless characters. 



The second part of the book deals with certain aspects of inberitance 

 and natural selectiou in man, especially with regard to disease and the effects 

 of alcohol. Disease is the chief factor in natural selection in civilised man, 

 and in general the organism reacts to the disease so as to confer immnnity 

 against that particular disease. But immunity is of very different kinds in 

 different diseases. In the case of some, where the disease is deadly, the race 

 develops inborn immunity by the elimination of those individuals which are 

 Busceptible; in the case of others nearly all individuals are susceptible. but 

 they have developed the power of acquiring immunity by reactioo of the 

 organism against the disease-germs. Europeans have largely developed inborn 

 immunity against tuberculosis, and the power of acquiring immunity against 

 measles. Negroes are very susceptible to tuberculosK but have a much greater 

 power of acquiring immunity from malaria tban have Europeans. The same 

 kind of tbing is seen with regard to alcohol; races which have long used it 

 in abundance are immune to its ill effects, while it rapidly destroys races 

 «hieb are unaecustomed to it. The study both of disease and of alcohol shows 

 the falsitj of the commonly aeeepted view that disease and the abuse of alcohol 



lead to degeneration, for the races that have l d mosl ezposed are not de- 



Renerate. but on the contrary are the most resistanl to the ill effects, owing 

 to the elimination of the susceptible individual- and the Belectioo of the 

 resistant. 



The later chapters deal with instinet and reason, memory, nature and 

 nurture. education etc. There is an appendix in which the author's general 

 ideas are reduced to diagrammatic tonn by Pro£ 11. EL Turner. 



Don saster (Cambridge). 



Zentralblatt f. allgp. u. cxp. Biologie. I. 45 



