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BEITISH ASSOCIATION FOR THE ADVANCEMENT OF 

 SCIENCE, AUSTRALIA, 1914. 



Address by Professor William Bateson, M.A., F.R.S., President. 

 (Continued from p. 318.) 



Paet II. — Sydney. 



At Melbourne I spoke of the new knowledge of the properties of 

 living things which Mendelian analysis has brought us. I indicated 

 how these discoveries are affecting our outlook on that old problem 

 of natural history, the origin and nature of Species, and the chief 

 conclusion I drew was the negative one, that, though we must hold 

 to our faith in the Evolution of Species, there is little evidence as to 

 how it has come about, and no clear proof that the process is con- 

 tinuing in any considerable degree at the present time. The thought 

 uppermost in our minds is that knowledge of the nature of life is 

 altogether too slender to warrant speculation on these fundamental 

 subjects. Did we presume to offer such speculations they would 

 have no more value than those which alchemists might have made 

 as to the nature of the elements. But though in regard to these 

 theoretical aspects we must confess to such deep ignorance, enough 

 has been learnt of the general course of heredity within a single 

 species to justify many practical conclusions which cannot in the 

 main be shaken. I propose now to develop some of these conclusions 

 in regard to our own species, Man. 



In my former Address I mentioned the condition of certain 

 animals and plants which are what we call " polymorphic." Their 

 populations consist of individuals of many types, though they breed 

 freely together with perfect fertility. In cases of this kind which 

 have been sufficiently investigated it has been found that these 

 distinctions — sometimes very great and affecting most diverse features 

 of organization — are due to the presence or absence of elements, or 

 factors as we call them, which are treated in heredity as separate 

 entities. These factors and their combinations produce the char- 

 acteristics which we perceive. No individual can acquire a particular 

 characteristic unless the requisite factors entered into the composition 

 of that individual at fertilization, being received either from the 

 father or from the mother or from both, and consequently no 

 individual can pass on to his offspring positive characters which he 

 does not himself possess. Rules of this kind have already been traced 

 in operation in the human species ; and though I admit that an 

 assumption of some magnitude is involved when we extend the 

 application of the same system to human characteristics in general, 

 yet the assumption is one which I believe we are fully justified in 

 making. With little hesitation we can now declare that the 

 potentialities and aptitudes, physical as well as mental, sex, colours, 

 powers of work or invention, liability to diseases, possible duration 

 of life, and the other features by which the members of a mixed 



