COMPOUND ORGANISMS 189 
Nevertheless it has not wholly lost its chloro- 
phyll, and it is of special interest to find that 
if it happens to grow where it cannot obtain 
plenty of nourishment from its host plant, 
a larger amount of chlorophyll can be 
formed; the stems, indeed, may even become 
distinctly green. Such an observation as 
this clearly indicates how closely the forma- 
tive processes of a plant are bound up with its 
nutrition. But the extreme readiness with 
which the dodder responds to an appropriate 
stimulus, by the production of suckers, is 
shown by the fact that if one of the stems of 
the parasite happens to twine round another 
one, they commonly pierce one another with 
the suckers which are immediately produced 
at the places of contact. 
CHAPTER XVII 
COMPOUND ORGANISMS 
It would be an error to imagine that all 
the flowering plants in which the production 
of chlorophyll is arrested are therefore to be 
