50 H. C. SORBY. 
Now, although this table must be looked upon as merely a 
first attempt, yet the results appear to be sufficiently definite 
to warrant some provisional general conclusions. 
The Spongilla is distinguished from the red group of alge, 
not only by the absence of the characteristic red and purple 
substances soluble in water, but by the presence in the 
Spongilla of yellow chlorophyll and yellow xanthophyll, 
which are absent in the case of red alge. ‘There is a closer 
relation between Spongilla and the green alge, but they con- 
tain a relatively far larger quantity of yellow chlorophyll. 
The lichens differ from the sponge, not only in containing a 
relatively larger amount of the lichnoxanthine soluble in 
carbon bisulphide, but are still more distinguished by con- 
taining much of the modification insoluble in that reagent, 
which is absent in the case of the sponge. In other respects 
there is a very strong analogy, since the relative amounts of 
blue and yellow chlorophyll and of the three different kinds 
of xanthophyllare almost identical. Comparing the most per- 
fectly developed specimens of the Spongilia and of the 
highest classes of plants, it is distinguished by containing 
relatively less yellow chlorophyll, less yellow xanthophyll, 
and very much less orange xanthophyll, and by the pre- 
sence of an entirely different yellow substance soluble in 
water, perhaps identical with one found in many fungi. The 
Spongilla is, however, completely distinguished from fungi by 
the chlorophyll and xanthophyll, which are quite absent from 
them. ‘Though there is thus no qualitative difference between 
the colouring matters found in Spongilla and in plants, yet 
in none of the above-named classes do they agree in their 
exact quantitative relations. Some light is, however, thrown 
on the subject by examining the change in their relative pro- 
portions in variously developed individual leaves or portions 
of the Spongilla. By comparing-together the more or less 
completely developed leaves in large buds, I find that in 
their earliest stage of growth, before being exposed to any- 
thing more than the weak light which penetrates through the 
exterior leaves, the amount of blue chlorophyll is very small, 
and that of the yellow chlorophyll relatively smaller than 
normal. In comparison with the amount of xanthophyll, 
there is an abnormally small quantity of orange xanthophyll 
and yellow xanthophyll, but greater of lichnoxanthine. As 
development proceeds the orange xanthophyll soon attains its 
normal proportion, whilst the other yellow constituents have 
undergone very little relative change and the amount of 
chlorophyll is but shghtly increased, that of the yellow 
chlorophyll being still abnormally less in relation to that of 
