THE CHLOROPHYLL APPARATUS 159 
brought about by the chloroplast as certainly as is the 
original change of the carbon dioxide. 
We have so far assumed that a sugar having the formula 
C,H,,0,, and known as a hexose, is the first carbohydrate 
formed. This, however, is not certain. Some experi- 
ments carried out in 1892 by Brown and Morris point 
rather to cane-sugar as the first carbohydrate synthesised. 
Cane-sugar is a more complex substance, and has the 
formula C,,H,,0,,. This conclusion was based on repeated 
observations that when leaves of Tropewolum were plucked 
and then exposed to sunlight for twelve hours, there was a 
great accumulation of this sugar in the leaf, while the 
simpler hexoses did not increase in quantity. The severance 
of the leaves from their stems prevented the transport of 
the sugars to any other part of the plant, so that they accumu- 
lated at the seat of their formation. 
Further investigations on this point are, however, necessary 
before a definite conclusion can be arrived at. It is not 
impossible that the cane-sugar of Tropeolum may be a 
form of stored material temporarily deposited as starch is. 
This theory of the processes of photosynthesis is by no 
means the only one which has been advanced, though on 
the whole it is that which has been received with most 
favour. A modification of Baeyer’s view was advanced by 
Erlenmeyer, who suggested that the first interaction of 
carbon dioxide and water leads to the formation of formic 
acid and hydrogen peroxide, according to the equation 
CO, + 2H O = HCOOH + H,0., and that then they are 
decomposed, yielding formaldehyde and water, and giving 
off oxygen, HCOOH + H,0, = HCOH + H,0 + 03. 
A theory of a totally different nature was advanced some 
years ago by Vines. Starting with the observation that 
a carbohydrate substance (cellulose) is produced or secreted 
by protoplasm in the process of the thickening of cell-walls, 
and noticing the formation of starch grains in the chloroplast 
almost as soon as the photosynthesis has been established, 
he argued that the carbohydrate is not directly formed 
