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PREFACE 



IN an address to the North British Branch 

 of the Pharmaceutical Society, by J. Arthur 

 Thompson, Professor of Natural History in 

 the University of Aberdeen, delivered in 1901, 

 the following passage occurs : 



" Even in my few illustrations I have prob- 

 ably made mistakes by touching subjects which 

 are beyond my field of work, but to pounce 

 upon these is to ignore the whole aim of my 

 address, which is to suggest that the various 

 departments of science yours and mine and 

 that of others are all correlated. It is not 

 solely by the aloofness of specialism, but by 

 mutual interest, and active co-operation as 

 well, that we make progress in understanding 

 the one problem which, in some form or other, 

 is before us all The Order of Nature." 



In the following pages, I may perhaps to 



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