30 Outline of Genetics 



seventeen species the changes are so great that the plants 

 have apparently been transformed into distinct alpine 

 "species." The reverse experiment, transplanting alpine 

 plants to the lowlands, gave similar but less startling 

 results. 



These experiments as they stand are really more serv- 

 iceable to the ecologist than the geneticist. The geneti- 

 cist wishes to know whether the transformations will 

 maintain themselves when the plants are returned to 

 their original stations and propagated by seed. Bon- 

 nier has as yet made no clear statement on this latter 

 point. 



An interesting issue arises in this connection. If the 

 transformed plants, after being returned to their original 

 stations, revert, in the course of a number of generations, 

 are we to conclude that inheritance of acquired char- 

 acters has not taken place ? Should we not rather expect 

 that, if inheritance of acquired characters takes place 

 under a given set of conditions, the reverse conditions 

 will bring the reverse change according to exactly the 

 same principle ?' Such work as that of Bonnier may 

 eventually demonstrate that inheritance of acquired char- 

 acters is a possibiUty in plants, though it may fail to 

 demonstrate that irreversible evolution can be brought 

 about through inheritance of acquired characters. The 

 latter can be fully demonstrated only when an acquired 

 character comes to be represented by a gene or set of 

 genes in the germ plasm, which are as definitely and 

 "permanently" a part of the hereditary complex as any 



^ It is of course true that some evolutionary changes are probably 

 irreversible (Herrick 12), but such changes are probably not involved 

 in the Bonnier experiments. 



