Nutrition Favors the Anomaly 



309 



The most susceptible stage seems to be that of the 

 young embryo in the ripening seed, for external in- 

 linences show their greatest effect 

 on seed-plants. But they also play 

 a part in vegetative methods of 

 propagation and operate in the 

 same direction, though as a rule 

 with less intensity. 



The gap between anomalies and 

 normal active characters is bridged 

 by a complete series of normal, la- 

 tent characters. These too are de- 

 pendent on external conditions in 

 just the same way as the other two 

 are. As a general rule we may 

 state that, within the specific range 

 of its character, the form of an 

 organ is determined by external 

 physical influences.^ 



As an instance let me cite the 

 result of some experiments with 

 the germination of potato seeds.- 

 The first leaves of the seedlings are 

 simple (Fig. 56), and the follow- 

 ing ones gradually approach the 

 peculiar pinnate form of those of 

 the grown plant. If the germina- 

 tion takes place in the garden, in 

 full sunlight, the plant develops 

 quickly and the various steps in 

 the development of the leaf- form 



^ Keimungsgeschichfe der Kartoffelsamen in Landvvirthsch. Jalir- 

 biicher, VII. Jahrg., 1878, p. 35. 

 'Lor. cif., p. 35. 



Fig. 56. Seedling of po- 

 tato grown under un- 

 favorable conditions 

 of light. From i to 6 

 the form of the leaf 

 increases in complica- 

 tion, but from 8 to 12 

 it decreases again. 

 Cultivated in a room 

 in 1876. 



