The Making of Species 



fascinating though it be, is not one that can be 

 discussed adequately in a general work on 

 evolution. Those interested in the subject are 

 referred to Professor Thomson's Heredity, and 

 to the address given by Professor E. B. Wilson, 

 of Columbia University, before the American 

 Association for the Advancement of Science, 

 which was fully reported in the issue of Science, 

 dated January 8, 1909. 



Stated briefly, then, our conception is, that 

 the fertilised egg is composed of a number of 

 entities, to which we have given the name 

 " biological molecules," because in certain 

 respects their behaviour is not unlike that of 

 chemical molecules. 



The units which compose these molecules, 

 being made up of protoplasm, are endowed with 

 all the properties of life, including the inherent 

 instability which characterises all living matter. 



We suggest that the continuous or fluctuating 

 variations that appear in the adult organism may 

 be the result of individual differences in the 

 biological "atoms" that compose the molecule. 



Discontinuous variations, or mutations, on the 

 other hand, may be the result of a rearrangement 

 of the atoms within the biological molecule. 

 Upon what causes this rearrangement it would 

 not be very profitable to speculate in the present 

 state of our knowledge. To do this would be to 

 inquire into the cause of a re-grouping of entities 



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