PRESIDENT’S ADDRESS. 17 
interpret all those intergrading forms which breed true and are not 
produced by factorial interference. 
It is to be inferred that these fractional degradations are the con- 
sequence of irregularities in segregation. We constantly see irregulari- 
ties in the ordinary meristic processes, and in the distribution of somatic 
differentiation. We are familiar with half segments, with imperfect 
twinning, with leaves partially petaloid, with petals partially sepaloid. 
All these are evidences of departures from the normal regularity in the 
rhythms of repetition, or in those waves of differentiation by which the 
qualities are sorted out among the parts of the body. Similarly, when 
in segregation the qualities are sorted out among the germ-cells in 
certain critical cell-divisions, we cannot expect these differentiating 
divisions to be exempt from the imperfections and irregularities which 
are found in all the grosser divisions that we can observe. If I am 
right, we shall find evidence of these irregularities in the association 
of unconformable numbers with the appearance of the novelties which 
I have called fractional. In passing let us note how the history of the 
Sweet Pea belies those ideas of a continuous evolution with which we 
had formerly to contend. ‘The big varieties came first. The little ones 
have arisen later, as I suggest by fractionation. Presented with a 
collection of modern Sweet Peas how prettily would the devotees of 
Continuity have arranged them in a graduated series, showing how 
every intergrade could be found, passing from the full colour of the 
wild Sicilian species in one direction to white, in the other to the 
deep purple of ‘ Black Prince,’ though happily we know these two to be 
among the earliest to have appeared. 
Having in view these and other considerations which might be 
developed, I feel no reasonable doubt that though we may have to 
forgo a claim to variations by addition of factors, yet variation both by 
loss of factors and by fractionation of factors is a genuine phenomenon 
of contemporary nature. If then we have to dispense, as seems likely, 
with any addition from without we must begin seriously to consider 
whether the course of Evolution can at all reasonably be represented as 
an unpacking of an original complex which contained within itself the 
whole range of diversity which living things present. I do not suggest 
that we should come to a judgment as to what is or is not probable in 
these respects. As I have said already, this is no time for devising 
theories of Evolution, and I propound none. But as we have got to 
recognise that there has been an Evolution, that somehow or other the 
forms of life have arisen from fewer forms, we may as well see whether 
we are limited to the old view that evolutionary progress is from the 
simple to the complex, and whether after all it is conceivable that the 
process was the other way about. When the facts of genetic discovery 
become familiarly known to biologists, and cease to be the preoccupa- 
1914, Cc 
