42 HEREDITY AND ENVIRONMENT 



and functions are inseparable and that any- 

 thing which modifies one of these must of 

 necessity modify the other also; they are 

 merely different aspects of organization, and 

 are dealt with separately by the morphplogists 

 and physiologists only as a matter of conven- 

 ience. At the same time there can be no doubt 

 that minute changes of function can frequently 

 be detected where no corresponding change of 

 structure can be seen, but this shows only that 

 physiological tests may be more delicate than 

 morphological ones. In certain lines of mod- 

 ern biological work, such as bacteriology, 

 cytology, and genetics, many functional 

 distinctions are recognizable between or- 

 ganisms morphologically indistinguishable. 

 But this does not signify that functional 

 changes precede structural ones, but only that 

 the latter are more difficult to see than the 

 former. For every change of function it is 

 probable that an "unlimited microscopist" 

 could discover a corresponding change of 

 structure. 



