8 
JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
To keep strictly within my experiences, I must explain that 
this is the result of all my experiments as regards litmus, and of all 
but that on the Yine as regards lithia. The experiment as to lithia 
in the uncut side of the Yine could not he tested, because I sent 
Professor Church the portions of the plant to be tested all cut up 
transversely, asking him to cut certain specified ones longitudinally, 
and then test the portions separately ; but he explained that that 
would be a delusive test after the portions had travelled from 
London to Cirencester, for the lithia would have had time to pass 
by endosmose and exosmose from one side to the other, after the 
plant was cut in pieces—which of course it would, for there was no 
longer any current to prevent its infiltration ; but the distribution 
of the litmus when the plant was newly cut showed clearly enough 
what the result of a search for lithia would have been at that time. 
To my mind this is conclusive on the question. Sachs must be 
wrong; and we must now re-examine his arguments, and see where 
the flaw lies. If the Committee will allow me a few minutes, I do 
not think we shall have very far to seek. His position is thus 
stated in his “ Physiologie Yegetale ” :— 
“ The absolute necessity (says he) of the intervention of light 
for assimilation in plants with chlorophyll is proved directly by 
their mode of development in darkness. "When we cause seeds to 
germinate in such conditions, roots, internodes, and leaves are 
developed generally in proportion to the mass of the seed. When 
all the provision of elaborated principles contained in it are 
exhausted, the development ceases. If up to that period the seed 
is allowed to germinate in the light, and it is then removed into 
darkness, the result is the same—the young leaves, although green, 
assimilate nothing; but if they are allowed to remain long enough 
in the light to have assimilated a little, there will be developed in 
darkness leaves and internodes until that new provision be exhausted 
also.” 
But there is one important fact that Sachs omits to keep in view 
here. If the plant in darkness assimilates nothing, neither does it 
take any food to assimilate. It is well known that plants do not 
feed in the dark, and nothing is easier than to prove it by experi¬ 
ment. Let any one with a Hyacinth growing in water in a glass, 
mark by a thread or narrow strip of paper glued to the glass the 
height at which the water stands at night; he will find it at the 
same height to-morrow morning, but very different to-morrow 
night. But the fact that they do not feed at night is universally 
acknowledged. 
