340 The Morality of Nature 



the environment in which they Hve, which promptly evokes, 

 not only the desired changes of character, but produces visi- 

 ble changes in form and habit as well. It is true that a 

 return to former environment will reproduce approximately 

 the former character, but even that shows continued flexi- 

 bility. It is more than probable that some of these bacilli 

 are permanently changed, in continued variation. Certain 

 germ diseases, for example, have less virulence now, than 

 in the historic past, and this is probably due to a modification 

 of the bacteria, as well as to improved sanitation for the 

 human victim. It is clear that just as the changes in life 

 character are due to change of environment, so the only 

 way by which a species is preserved unchanged, is by contin- 

 uance of unchanging environment. After reaching an 

 adaptation to environment nearly perfect, and a balance 

 between production and destruction which prevents over- 

 crowding, or habits by which overcrowding is endured and 

 relieved (such as spore producing habit), a creature may 

 continue without change, and so without progress. 



But when environment changes, the creature changes; 

 and if the same changed condition persists, the correspond- 

 ing change in the creature continues or increases; and as 

 soon as it reaches a certain definition it becomes a part of 

 the heredity, and is transmitted to offspring, we may assume, 

 by a new addition to, or change in, the recent substances of 

 the nucleus. A particle of protoplasm has been added to the 

 chromosome series, which is a self -registering heredity sam- 

 ple, of what was current when the feature was formed. And 

 in the redevelopment of that chromosome, when that particle 

 is reached it will react again as it does now. Now there is 



