II. 



ON HEREDITY. 



With your permission I wish to bring before you to-day my 

 views on a problem of general biological interest — the problem 

 of heredity. 



Heredity is the process which renders possible that per- 

 sistence of organic beings throughout successive generations, 

 which is generally thought to be so well understood and to 

 need no special explanation. Nevertheless our minds cannot 

 fail to be much perplexed by the multiplicity of its manifesta- 

 tions, and to be greatly puzzled as to its real nature. A celebrated 

 German physiologist says ^, 'Although many hands have at all 

 times endeavoured to break the seal which hides the theory of 

 heredity from our view, the results achieved have been but 

 small ; and we are in a certain degree justified in looking with 

 little hope upon new efforts undertaken in this direction. We 

 must nevertheless endeavour from time to time to ascertain 

 how far we have advanced towards a complete explanation.' 



Such a course is in every way advisable, for we are not 

 dealing with phenomena which from their very nature are 

 incomprehensible by man. The great complexity of the sub- 

 ject has alone rendered it hitherto insuperable, but in the 

 province of heredity we certainly have not reached the limits 

 of attainable knowledge. 



From this point of view heredity bears some resemblance to 

 certain anatomical and physiological problems, e. g. the struc- 

 ture and function of the human brain. Its structure— with so 

 many millions of nerve-fibres and nerve-cells— is of such extra- 

 ordinary complexity that we might well despair of ever com- 

 pletely understanding it. Each fibre is nevertheless distinct in 



^ Victor Hensen in his ' Physiologic der Zeugung,' Leipzig, i88r, p. 216. 



