Recent Advances in the Study of Heredity. 11 
arose. The paper as it stands is no more than a bald statement of 
the experiment which I conducted, and was in its first form, pre¬ 
ceded by somewhat lengthy exposition of what I meant by the 
theory of ancestral contributions. This preliminary discussion was 
not included in the paper as it appeared in the Proceedings of the 
Royal Society ; and the fear, which I felt at the time, lest this 
omission should lead to misapprehension proved to be well founded. 
I do not by any means hold that “ the theory of inheritance 
summed up in the ‘ law of ancestral heredity’ ” would be invalidated 
by the result of the investigation which I conducted. Let me 
attempt to make my position clear. 
The last twenty years have witnessed a gradual but profound 
change in our conception of the relation between successive 
generations of organisms. This revolution, which was initiated by 
the publication of Weismann’s doctrine of the continuity of the 
germ-plasm, and is still far from being complete, consists in the 
substitution of the doctrine that new characters arise in the germ- 
plasm and, once arisen, owe their existence in subsequent genera¬ 
tions to their existence in potentid in the germ-plasm, for the old 
view that characters arise in the soma and are in some way impressed 
on the germ-plasm to which that soma gives rise. So long as the 
older (in a sense, Lamarckian) view was held, the chief task before 
the student of heredity was to supply a hypothesis to explain how 
the character arising in the soma was transferred to the germ-plasm. 
It is not commonly realised how long this “Lamarckian” view of 
the question has persisted ; nor how deeply it has been engraven on 
the imagination. That Darwin’s conception of heredity was 
essentially of this nature is shown by the fact that his theory of 
Pangenesis was par excellence a theory to account for the trans¬ 
ference of somatic characters from the soma to the germ-cells 
which it contains. 
It is my thesis that the general view of heredity, in which 
biologists have tacitly believed, and on which practical breeders 
have acted, until the last few years, has been the natural outcome 
and immediate offspring of that conception of the relation between 
successive generations of organisms in which the mature individual 
occupies a primary and the germ-plasm a secondary position. 
According to this general view of heredity, which I have called the 
Theory of Ancestral Contributions, and shall subsequently refer to 
as the contributional view, or theory, the characters of an organism 
