Rats on a Roundabout 167 



generation the aptitude to association-forming had 

 been so much increased that five lessons were enough. 

 Perhaps future generations will answer the bell with- 

 out any lessons at all. But apart from this possible 

 climax the experiments suggest that individual ex- 

 perience may have a specific and representative in- 

 fluence on the race. We refrain, however, from basing 

 any conclusion on Pavlov's experiment until we have 

 before us a full account of the circumstances and a 

 precise statement of the numbers. It may be noted, 

 however, that recent experiments on white rats by 

 Dr. E. C. MacDowell led emphatically to the conclu- 

 sion that offspring of trained parents or of trained 

 grandparents as well, take as long to learn the secret 

 of a maze as did those that were first trained. 



We wish, however, to refer to some other experi- 

 ments on this important question — whether individu- 

 ally acquired bodily modifications can be transmitted 

 to the progeny in a specific and representative fash- 

 ion. It will be understood, of course, that the rather 

 unfortunate term "acquired character" has a per- 

 fectly definite meaning, and that it is not open to any 

 "argufier" to use it in some other way. An acquired 

 character is "an exogenous somatic modification" — a 

 bodily change directly induced in the individual life- 

 time by some peculiarity or novelty in environment, 

 nutrition, or function, and so transcending the limit 

 of organic elasticity that it persists after the inducing 

 conditions have ceased to operate. 



Two psychologists in Philadelphia, Dr. Bentley 

 and Dr. Griffith, made the experiment of rotating 



