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, 

 Cheno podium, 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, Bil. Ver., xi. 822. 



2 Ann. Chim. Phys., xi, 62, 208; Ann. Chim. Pharm., 77, 295. 



3 Fliickiger, Pharmacognosie; Kamp, Ann. Chim. Pharm., 100, 300. 



4 Durocher and Lalaguti, Liebig's Agric. Chemie, 8. Aufl., 371. 



5 E. Riechardt, Chem. pharm. Centralbl., 268, 567. 



