16 Mutual Independence of Hereditary Characters 



velop into green shoots. By severing the stems, the 

 rhizomes of Mentha, Circaea, and many other plants, can 

 be made into ascending stems, and the transformations 

 which the thick almost resting rhizomes of Yucca undergo 

 after such treatment are remarkable. In a similar manner 

 Goebel has succeeded in causing the rudiments of bracts 

 to develop into green leaves,* and Beyerinck^ observed 

 even the transformation of young buds of Rumex Aceto- 

 sella into roots. 



In such cases it is clear that the possibility of develop- 

 ing in either of two different directions is dormant in the 

 young primordia. For this very reason I should like to ap- 

 ply the name dichogeny to this phenomenon. And it evi- 

 dently depends upon external influences what direction is 

 taken. Therefore a selection must take place from among 

 the available hereditary characters of the species, and this 

 selection may be influenced by artificial interference. For 

 the theory of hereditary characters such experiments are 

 therefore of the highest interest. 



Here are naturally included the phenomena of bud- 

 variation. Many of these are cases of atavism. Let us 

 select an example. In plants with variegated leaves one 

 frequently observes single green branches. Since the 

 variegated plant is descended from green ancestors, this 

 case is regarded as a reversion. The variegated individual 

 evidently still possessed the characteristics of the green 

 ancestor, though in a latent condition. During the bud- 

 formation it split its entire character, but in such a way 



*Goebel, K. Beitrage zur Morphologic und Physiologic des 

 Blattes. Bot. Zeit. 40: 353. 1882. 



^Bcyerinck, M. W. Beobachtungen und Betrachtungen iiber 

 Wurzelknospen und Nebenwurzeln. Veroffentl. Akad. Wiss. Am- 

 sterdam, pp. 41-41. 1886. Cf. also Tafel T, Fg. 9. 



