The Inlientance of Acquired Characters 19 



centage of double and sometimes triple grains. The author calls 

 this a typical case of inheritance of acquired characters, but Ameri- 

 can investigators have hesitated to accept this interpretation of 

 the phenomenon. Characters of practically the same sort have 

 been observed to originate in other cases in corn not known to 

 have been injured in any way. 



2. Effects of use and disuse. — Inheritance of 

 the effects of use and disuse lay at the foundation of 

 Lamarck's theory of evolution. Weismann was suc- 

 cessful in discrediting this belief by explaining on some 

 other basis practically all of the supposed examples of 

 this phenomenon that had been advanced. In plants, 

 of course, it would be hard to find anything exactly 

 analogous to the use and disuse of parts in animals; 

 Lamarck himself did not attempt to apply quite the 

 same theory to the plant kingdom. 



One fact, however, is a common experience of botanists. 

 Functionless organs gradually become aborted, become mere 

 vestiges or even suppressed entirely. For example, a study of the 

 organogeny of flowers shows that when a lloral member is belated 

 in its development it is destined sooner or later not to appear at 

 all. The following theoretical Weismannian (or Darwinian) 

 explanation of this situation is suggested. A given species has a 

 given nutritive capacity; the less it draws upon its nutritive 

 capital for the development of one organ the more it has available 

 to expend on the development of other organs. When an organ 

 becomes functionless it no longer has any survival value; survival 

 is then dependent upon the relative develoi^ment of the other 

 organs. Through "variation" certain individuals develop the 

 functionless organ less than usual and therefore develop the other 

 organs more than usual. Under the new conditions these individ- 

 uals will survive and the others will be eliminated. Gradually 

 abortion of functionless organs would lake [)lace in this waw 

 One would expect that the rate of change would be roughl>- pro- 



