Ill 
THE COLOURS AND PIGMENTS OF PLANTS 
59 
of the Protozoa, there is a constant oscillation between 
red and green as a ground colour. It seems most 
probable that this, as in higher plants, is due to 
a destruction of the chlorophyll green and a conse¬ 
quent predominance of an associated lipochrome. In 
Algse it occurs nowhere in such an instructive way 
as in the brittle-worts Chara and Nitella. Here 
virtually the whole plant is coloured green by chloro¬ 
phyll, but the reproductive organs, and especially the 
antheridia, as they ripen become a bright red, the 
colour being due to the red chromatophores which 
replace the chlorophyll corpuscles. The whole 
process is exactly analogous to that which occurs 
during the ripening of red fruits like the rose-hip. 
Quite similar is the process which occurs during 
the maturation of the antheridia of brown seaweeds 
like Fucus. Here the plant owes its colour to a 
combination of chlorophyll green, a brown pigment, 
and a lipochrome. In the oospheres all these three 
are retained, but in the antherozooids the brown 
and the green disappear, and the orange-coloured 
lipochrome remains in the chromatophores and gives 
rise to the orange coloration. The retention of the 
chlorophyll in the female elements and its disappear¬ 
ance from the male many would regard as an 
illustration of the greater vegetativeness of the 
female. These two examples may suffice to show 
that the processes which give rise to the colours of 
Angiosperms have very well-marked analogues among 
Cryptogams. 
