
BEHAVIOUR OF PLANTS TOWARD LIGHT: aa 
cotyledons open again. If we examine them at night 
when it is dark, we usually find them clasped together 
and erect. As the morning light comes on they open 
again. The light, then, must have an influence in 
spreading the cotyledons apart. oN 
SD a 
We should now refer to our = Af 
observations on the marrow seed- NW Z 
lings, grown in the dark, or if we Y Ss 
did not then observe the cotyle- ! j 
dons, we should at once examine | 
some seedlings of the vegetable 
marrow, grown in the dark, as 
shown in Fig. 164. The cotyle- 
dons remain closed. Fig. 169 is 

very interesting; the stem as it Fic.172. same seedlings after 
grows is obliged to push its way oe 
out from between the cotyledons at one side, so tightly 
are they clasped together. These cotyledons have never 
opened because they have been kept from the light. 
Arrangement of leaves in relation to light. The 
position of the leaves on plants, whether the plant 
is small or large, is such as to place the leaf so that 
it will receive an abundance of light. The relation of 
the leaves of a given plant to one another is such as 
to give all the leaves an opportunity to receive light 
with the least possible interference. Plants of several 
different types in this respect may be brought into the 
