SOURCES OF CHANGE 65 



accurate to regard these degrees as positive re- 

 sponses to varying conditions. The organism ad- 

 justs itself to fluctuations of environment and 

 any adjustment demands positive action. 



Some apparently non-adaptive responses of in- 

 dividuals seem more truly negative. Deficiency 

 diseases and less serious organic disturbances re- 

 sulting from dietary deficiencies are of this nature. 

 The lack of a vitamine or of iodine, or insufficiency 

 of either, is obviously a fluctuation of environ- 

 ment, but the human body usually lacks hereditary 

 power to effect an adjustment to it, and if it exists 

 in spite of the unusual condition, it does so in a 

 subnormal state. The thyroid disturbances arising 

 from lack of iodine, for example, result in positive 

 conditions in the body which constitute a clinical 

 picture, but they are no more than the results of 

 an abortive attempt at adaptation for they do not 

 fit the individual to meet the conditions which 

 cause them. 



When we consider these cases thoroughly we find 

 that they are not different, however, from adaptive 

 responses, even though they are more obscure. Our 

 reaction to fiuctuations of iodine or vitamine intake 

 are not considered until these substances fall below 

 the necessary minimum and disease results. If 

 tanned skin were not visible our response to sun- 

 light would probably be just as much neglected, 

 but let sunlight be reduced below the necessary 



