to organise, and to harmonise the phenomena of development which 
is not material and which is not a form of energy. It is a conception 
for which Driesch has used the term Enteleehy. For my part I con- 
sider the more correct attitude can be expressed by the statement of 
T. II. Morgan 1 : — “We cannot see how any known principle of chem- 
istry or physics can explain the development of a definite form by 
the organism or a piece of the organism.” We ,may consider this a 
fair result of the discussion of the events of animal embryology, but 
it must be emphasised that it is not a proof of the existence of any 
non-material factor. It does not mean that we may never explain 
development by material agency; it is merely the expression of our 
present ignorance of a factor or factors which are responsible for or- 
ganising and co-ordinating, and which are characteristic of living 
protoplasm. 
I shall pass over the phenomena of regeneration in the adult or- 
ganism, but I may call your attention to the regeneration of the lens 
in the eye of the salamander after removal of this structure. The 
new lens arises from the already differentiated layers of the iris, 
whereas in normal original development it takes its origin from the 
ectoderm. That is to say, a highly specialised structure, the lens, 
arises out of a tissue which is highly specialised in another direction. 
Time will not allow of a discussion of this and other problems of 
regeneration here. Let us pass to the second group of phenomena 
that were mentioned at the outset: — The phenomena of Evolution 
or Transformism. During the past few years several Avriters on bio- 
logical subjects, whilst accepting the general conception of Evolu- 
tion, have hinted that they considered the explanations put forward 
as insufficient to account for the phenomena. For example, Bate- 
son, in his Presidential Address to the British Association for the 
Advancement of Science last year at Sydney, used these words, “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 evi- 
dence as to how it has come about, and no clear proof that the process 
is continuing in any degree at the present time.”' This statement 
came, I am afraid, as a great shock to the general public and even to 
many scientists, especially to those non-biologists who have regarded 
Darwin’s suggestions as all sufficient. It even resulted in newspaper 
correspondence suggesting that all evolution was a myth ! I need 
scarcely point out that this was due to the very prevalent idea that 
Darwinism and Evolution are one and the same thing. It is only 
natural that with our modern technique and our accumulated know- 
ledge of the phenomena of Nature we should endeavour to explain 
more fully the causes and methods of Evolution and to seek for ex- 
planations of the difficulties that Darwin himself felt in the accept- 
ance of his theory. Let us leave on one side to-night the modifica- 
tions to Darwin’s theories now considered necessary owing to the 
1 T. H. Morgan. Regeneration. 
