87 
showed by their lighter blue that they had lost much of what 
they had stored up in the morning. This, I think, can be ac- 
counted for, only by supposing the transmission to take place 
more slowly, since it is impossible to assume that the reduc- 
tion of carbonic acid should be accelerated in rainy weather. 
If my attention had been sooner drawn to the change of 
colour in the early morning and my stay in the floral para- 
dise of Buitenzorg had been longer, I should doubtless have 
found opportunities for testing in a more decisive way the 
supposed influence of light on the transmission of organic 
matter; as it is I must rest content with having pointed out 
the probability of its existence. If this influence should after- 
wards be demonstrated, also the slow growth of shadeplants, 
to the feeble respiration of which Mayer ') has recently called 
attention, might be accounted for by the slow transmission of 
assimilation products to the places of consumption. 
The extreme slowness of the growth of the tobaccoplants 
which Sachs cultivated in pots*), would for the same supposed 
reason not, perhaps, have been so striking, if instead of being 
placed at a window, the plants had been in full day-light. 
If now we return to the figures expressing the absolute quan- 
tities of food produced by four thriving plants in the tropics 
(p. 80); and if we remember how slight the transmission is 
during 12 night-hours, it is evident that the visible production 
by day and loss by night, cannot possibly account for the 
quantities of matter necessary for a vigorous tropical growth. 
It may be true that the figure for Delima is a high one, but 
as we have seen, the weight of one M* becomes equal to its 
weight at the beginning of the day, even before sunset. More- 
over Connarus clearly showed that though leaves which have 
been exposed to the full sun before 12, lose much of their 
surplus-gain in the afternoon, yet they retain enough to cover 
the nightly loss. I may add that a cloudy sky and to a far 
1) Verslagen en Mededeelingen der Kon. Akad. van Wetenschappen. Afd, Nataurk. 
3e Reeks, Dl. IX, p. 272. 
2) 1. c. p. 1. 
