1887] Comparative Chemistry of Higher and Lower Plants. 801 
_ of late summer illustrates the transmutation of color which may 
__ be observed in plants, and I would suggest that this same 
_ gradation may be seen on the large evolutionary planes of all 
plant groups, chlorophyll, like the plants, being at different 
= evolutionary stages; for example, in many Algz and lower 
plants it appears as light bright greens, and finally in the darker 
greens of the higher plants. 
Considering in general the chemical compounds of flowering 
plants among the apetals and monocotyledons on the first evolu- 
tionary plane, where the plant elements are simple, tannin, wax, _ 
starch, aromatic or acrid principles, and the oils and sugar of 
€ palm are the most conspicuous substances. These com- 
pounds are found in the same or in neighboring plants, and their 
= @sociation is doubtless of evolutionary significance. Gluco- 
_ Sides or alkaloids, though occurring in some few of these plants, 
_ “e not characteristic of this stage of evolution. 
Í Tannin is a general name for a class of substances which 
_ Presents many aspects in different plants. It first appears, as was 
Stated, in the liverworts, combined with large quantities of starch 
= and Wax; then in ferns. Among the amental apetalous groups 
= tis one of the conspicuous compounds, also associated with 
: ‘Starch; the Casuarina, willow, poplar, hazel, oak, beech, chestnut, k 
x alder, and birch containing large quantities. Tannin is widely 
Pe distributed, though especially in the leaves, barks,’ seeds, and 
: ene of fruits, and in other plants in considerable quantities, as 
2 ie maple, sumach, tea, in many berries, the holly, and the 
_ Seeds and stalks of the grape-vine. 
oe ormentilla erecta? Rosacee, yields six to twenty per cent 
? tannin, and, although this compound is present in mono- and 
bor tyledonous plants, it seems to be more prominent in the 
pee on the first evolutionary plane, and to occur less, if at 
eon the highest plants. When it is remembered that tannin is 
. hse in greater abundance in lower plants, which I have com- 
be formative to the formed or higher evolutionary groups; 
ER still further illustration of what was stated about the higher 
Physic, of ash-constituents in lower plants. 
eS lologists differ as to the tannin functions in plants. It 
\ eee 
Repartiti : ; - 
la Science du Tannin dans les diverses Regions du Bois de Chene,” Ane as 
i TSS, Ergebnisse, Landw. Versuche, München, 1861. 
