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species apart from Natural Selection and all the limita 
tions which that theory presupposes. 
The appearance of an individual with a considerable 
divergence from the normal type, and the power of that 
individual to impress its special likeness on its descend 
ants, is another source of necessary transmutation. The 
principle of correlation of growth, which is necessary for 
the conversion of one co-ordinated structure into another, 
has also to be taken account of. And finally, we have to 
remember that it is quite certain that some of the factors 
must sometimes work together, and the result of their 
common action will be proportionately great. 
It may well be that there are other factors of Organic 
Evolution yet to be discovered. It may be that living 
matter may have a tendency to develope in a certain way 
in consequence of its particular composition. I mean 
that it may be possible that there should be a connection 
between certain organic combinations and the forms 
which they produce, just as there is a tendency in certain 
chemical compounds to crystallise in a special manner. 
But whether this last contention can be sustained or not, 
it suffices for my present purpose to affirm that the argu 
ments for Organic Evolution in their abstract form are 
independent of any arguments in favour of a particular 
law through which this evolution has taken place ; that so 
far as they are cogent (and their cogency is generally 
admitted), we are compelled to believe that there must be 
efficient agencies to bring about this result ; and that we are 
already in possession of many facts which tend to confirm 
that belief. When investigation shall have been carried still 
further, I believe that new facts will be discovered tending 
in the same direction. The process may be a long one. 
Favourite theories, supported by the majority of scientific 
investigators, will not be relinquished at once. But the