98 
UPWARD GROWTH OF THE HEAD, AND [Part II. 
Crane-neck 
growth of first 
gemmule, to 
shield it while 
forced through 
the earth. 
Roots grow 
through the 
earth with very 
little force. 
much as to name the agent which directs the 
growth of the root, tap or branch. 
When the gemmules reach the air the agent 
appears to be light. At least, when the gem- 
mules reach the air this straight upward ten¬ 
dency is immediately overcome by light. These 
stems, after having forced themselves straight up¬ 
wards through eight or ten inches of earth, were 
drawn away from the spot where each emerged 
from the earth by light through the holes at the 
centre of the flower-pot. The plants were still 
crane-necked; that is, their heads were doubled 
on their stems as they came out of the seeds: 
and thus, while the stem of a plant, whose seed 
has two divisions or cotyledons, is forcing its 
way upward, its head is pointed downward, and 
the leaves are drawn through the earth with the 
grain . But for the contrivance of the crane- 
neck, the leaflets, owing to their branching and 
expending one from the other, must be broken 
and torn to pieces by the great force necessary 
to thrust them and the stems bodily through the 
earth. This is a very beautiful provision. The 
roots, on the other hand, appear to grow in 
length through the earth, with very little, if 
any, pressure at all. This may possibly be in 
part owing to their elongating only at their 
