fruits were exalted by acids, and changed to purple 
or green by the addition of alkalis *. The forego- 
ing facts sufficiently prove, that the colourable mat- 
ter of fruits, like that of flowers, and of leaves, is ex- 
tracted by the same means, and acted upon, in a si- 
milar manner, by the same chemical agents ; where* 
fore we are entitled to conclude, that its nature is 
essentially the same, and that it exhibits different ap- 
pearances and colours, according to the modified 
action of those causes which produce the colouration, 
of all the other parts of the plant. 
410. The process of maturation, during which, 
the changes of colour in fruits principally take place, 
is known to be accompanied by spontaneous changes, 
under which acid matter is developed, and produces 
effects on the colour of fruits not unlike those which 
decomposition occasions in the leaves, at the period 
of their fall. Whatever be the nature of the acid de* 
veloped, its power in producing changes in the co- 
lourable matter will, probably, be nearly the same j 
and the existence of such acid is often sensible to the 
taste, though disguised frequently by the presence of 
saccharine matter. It is a farther confirmation of 
these views, that green fruits, like other green parts 
of plants, were found by M. de Saussure (274.) ta 
afford oxygen gas in sunshine; which fact evinces, that 
they not only previously contained carbonic acid, but 
that, as in other cases, they became green, when this 
acid was decomposed and expelled. 
* Mem. Phys. Chim. torn, iii, p. 153. 
