9 
basis for further generalizations, or, if a farmer, he may derive many 
suggestions, hints, and rules by which to improve his methods. 
Very few appreciate the extensive range of edible plants, but the 
lists given by E. L. Sturtevant (Agr. Sci., Vol. IIL, p. 174) suggest 
that we have in the botanical world an almost unexplored field from 
which to recover for the use of civilized man an endless variety of 
foods and fruits unknown to our present cuisine and table. Sturte- 
vant enumerates in detail the 210 natural orders of plants recognized 
by botanists from the days of Linnzus to those of Bentham and 
Hooker. These orders include 8,349 genera and 110,663 species, and 
Sturtevant shows that the edible plants include only 4,233 species, 
representing 170 of these orders, so that only about 34 per cent of the 
known species of plants are now being used as food—most of them, 
of course, to a very shght extent, only as auxiliaries to the principal 
foods. 
The food plants extensively cultivated by man include only 1,070 
species; that is to say, less than 1 per cent of all known species are 
cultivated anywhere throughout the known world, and those actually 
in ordinary use in European and American kitchen gardens represent 
only 211 species. The preceding numbers all refer to the phenogams, 
but Sturtevant gives supplementary lists covering the lower order of 
plants. 
Therefore it would seem that the present condition of agriculture 
and the present extent of our available vegetable foods is limited not 
so much by our climate and soil as by our ignorance of the laws of 
nature affecting plant life. We may not control the climate, but we 
may rear natural plants and adopt rational methods of modifying 
them by cultivation until they and we become quite independent of 
the vicissitudes of drought and frost. 
In conclusion I gratefully acknowledge the enthusiastic assistance 
that I have received from Mrs. R. 8. Hotze as translator, and Mr. 
E. R. Miller in the preparation of the index. 
