HIGHER AND LOWER PLANTS 263 
through the entire plant kingdom, for the largest ash-percent¬ 
ages are found among those plants lower in the evolutionary 
scale, which would correspond to the larger ash-percentage 
of younger, or formative, parts of the growing plants. Some 
of these lower groups, as the diatoms of the Algae and the vas¬ 
cular cryptogams, 1 contain enormously large ash-percentages; 
in the Horse-Tail, Equisetum , 2 60 per cent, alone of silicic 
acid. The Lycopodium , 3 in addition to 14 per cent, of silicic 
acid, contains 27 per cent, of alumina and 2.5 per cent, of 
manganese. Among comparatively lower plants the willow 
and poplar 4 are rich in ash-constituents; the former 5 con¬ 
tains 1.53 per cent, of manganese. Members of the sedge order 
and grasses contain large quantities of silica; the rice-hull, 98 
per cent. Various species of apetalous plants on the same 
evolutionary plane with these groups also contain a large 
percentage of ash-constituents, as the Salicornia, Salsola, 
Chenopodium, and A triplex, also the sugar beet. 
I have stated what chemical elements are essential for the 
life of the lower as well as the higher plants; also those 
which may occur in certain plants; and I have spoken of the 
two general classes of compounds of which plants are built 
as the volatile and ash constituents. The four elements, car¬ 
bon, hydrogen, oxygen, and nitrogen, enter into the composi¬ 
tion of the first class of compounds, and the grouping of these 
elements with each other and with the ash-elements, constitutes 
what is called plant chemistry. 
As certain chemical elements are always present in plants, 
so certain changes occur, and compounds are found gener¬ 
ally, more especially among the albuminous constituents. 
However, even this statement should be restricted to saying 
that the first chemical reactions between these elements are 
probably identical at the start, the subsequent compounds 
formed depending upon the evolutionary stage. 
The infinite variety of these compounds is only equalled by 
1 Die Pflanzensenstoffe, p. 323; W. Lange, Bit. Ver., xi. 822. 
2 Ann. Chim. Phys., xi, 62, 208; Ann. Chim. Pharm., 77, 295. 
3 Flückiger, Pharmacognosie; Kamp, Ann. Chim. Pharm., 100, 300. 
4 Durocher and Lalaguti, Liebig’s Agric. Chemie, 8. Aufh, 371. 
5 E. Riechardt, Chem. pharm. Centralbl., 268, 567. 
