2o Plant Genetics 



Mutilations in plants have received no serious 

 consideration; in fact, no one seems to have con- 

 sidered the possibility of such inheritance. Cuttings 

 for propagation, for example, are usually trimmed to 

 prevent excessive transpiration, but no one ever expects 

 to find this mutilation perpetuated, even in the plant 

 developed from the cutting, much less in the next 

 generation developed from seed. In fact, since we 

 have begun to learn of the remarkable powers of regenera- 

 tion possessed by plants and animals, we would not 

 expect the inheritance of mutilations. 



2. EFFECTS OF ENVIRONMENT. This has long been 

 a topic in botany. Trees deformed by prevailing winds, 

 like the willows that line the canals in Belgium and 

 Holland, or storm-crippled trees along exposed seacoasts, 

 are not known to produce progeny showing these char- 

 acters when the adverse environmental conditions are 

 removed. ZEDERBAUER, on the other hand, found that 

 Capsella, which in the course of many years had gradu- 

 ally crept along the roadside up into an alpine habitat 

 and there acquired alpine characters, retained these 

 characters when transplanted to the lowlands. This has 

 been accepted as an authentic instance of the inheritance 

 of acquired characters; but it is possible that this con- 

 quest of an alpine habitat by Capsella can better be 

 explained by the gradual natural selection of just those 

 germinal variations that best fitted individuals to cope 

 with alpine conditions. This would result in the gradual 

 establishment of a strain of germ plasm that would 

 produce body structures fitted to alpine conditions. 

 In other words, this is just the way in which natural 

 selection would develop a new elementary species 



