Nutrition Favors the Anomaly. 
309 
The most susceptible stage seems to be that of the 
young embryo in the ripening seed, for external in- 
fluences 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, \vithin the specific range 
of its character, the form of an 
organ is determined by external 
physical influences. 1 
As an instance let me cite the 
result of some experiments with 
the germination of potato seeds. 2 
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 
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. 
1 Keiv.mngsgeschichte der Kartoffchamcn in Landwirthsch. Tahr- 
biicher, VII. Jahrg., 1878, p. 35. 
2 Loc. cit., p. 35. 
