83 [Vol. xl. 
various areas material which can be assembled in one 
museum, and, secondly, that the museum man, with the help 
of his library of reference and such other collections as may 
be at his disposal, should patiently work out the material 
supplied. 
It is evident, therefore, that whereas the field-naturalist 
may be able to do his own work and, later on, part of that 
of the museum man also, the museum man cannot do a stroke 
of work without the help of the field-worker. 
To the modern field-naturalist one would therefore imagine 
trinomialism and all that it includes must be of the most 
absorbing interest, for it is only he who can supply us with 
the factors to elucidate all the causes giving rise to the 
variations which form geographical races. There is still 
much work for him to do. 
At present our knowledge of cause and effect is very 
crude. Certain broad rules we do know, but very little of 
the minutize or of the way in which these same broad rules 
conflict or combine. 
We know that humidity generally means deep and 
brilliant colouring, and drought the reverse. Dense tropical 
forests run much to black, but often a combination with it 
of most vivid colours. Snow and ice require their inhabi- 
tants to seek immunity from danger in white pelts or 
plumage. Animals and birds in deserts require sandy 
or pale plumage corresponding to their environment, and so 
on. We already know that some changes occur far more 
quickly than others, as for instance Beebe’s Dove, which 
changed from one race to another in its own lifetime, whilst, 
on the other hand, there are numerous instances of game 
and other birds, such as Sparrows in America, Mynas in 
Australia, in which there is as yet no apparent change 
taking place. In the latter we have the result of many 
generations of birds from which to draw our conclusions, 
but in Beebe’s bird we do not know what the result of the 
individual change would have been on the next generation, 
and whether the protoplasm had acquired the potentialities 
that a permanent change would entail. . 
