FOLIAGE LEAVES: THE LIGHT-EELATION 9 
and not too much. The danger from too much light is 
not the same in the case of all leaves, even on the same 
plant, for some are more shaded than others. Leaves also 
have a way of protecting themselves from too intense light 
by their structure, rather than by a change in their posi- 
tion. It is evident, therefore, that the exact position which 
any particular leaf holds in relation to light depends upon 
many circumstances, and cannot be covered by a general 
rule, except that it seeks to get all the light it can without 
danger. 
13. Fixed position. Leaves differ very much in the power 
of adjusting their position to the direction of the light. 
FIG. 2. The day and night positions of the leaves of a member (Amicia) of the pea 
family. After STKASBURGKR. 
Most leaves when fully grown are in a fixed position and 
cannot change it, however unfavorable it may prove to be, 
except as they are blown about. Such leaves are said to 
\YAvefixed light positions. This position is determined by 
the light conditions that prevailed while the leaf was grow- 
ing and able to adjust itself. If these conditions continue, 
the resulting fixed position represents the best one that can 
be secured under the circumstances. The leaf may not 
receive the rays of light directly throughout the whole 
period of daylight, but its fixed position is such that it 
probably receives more light than it would in any other 
position that it could secure. 
