THE ASH OF PLANTS. 145 
We easily see then, that, as circumstances are perpetual- 
ly making new varieties, so analysis continually finds di- 
versities of composition. 
9. Of all the parts of plants the seeds are the least liable 
to vary in composition. Two varieties or two individuals 
may differ enormously in their relative proportions of 
foliage, stem, chaff, and seed; but the seeds themselves 
nearly agree. Thus, in the analyses of 67 specimens of 
the wheat kernel, collated by the author, the extreme 
percentages of ash were 1.35 and 3.13. In 60 specimens 
out of the 67, the range of variation fell between 1.4 and 
2.3 per cent. In 42 the range was from 1.7 to 2.1 per 
cent, while the average of the whole was 2.1 per cent. 
In the stems or straw of the grains, the variation is much 
more considerable. Wheat-straw ranges from 3.8 to 6.9; 
pea-straw, from 6.5 to 9.4 per cent. In fleshy roots, the 
variations are great; thus turnips range from 6 to 21 per 
cent. The extremest variations in ash-content are, how- 
ever, found, in general, in the succulent foliage. Turnip 
tops range from 10.7 to 19.7; potato tops vary from 11 to 
near 20, ‘and tobacco from 19 to 27 per cent. 
Wolff, (Die naturgesetalichen Grundlagen des Ackher- 
baues, 3. Aufi., p. 117,) has deduced from a large number 
of analyses the following averages for three important 
classes of agricultural plants, viz.: 
Grain. Straw. 
Cereal crops 2 5,25 per cent. 
Leguminous crops) 3 5 ets ee 
Oil-plants 4 45 “ « 
More general averages are as follows, (Wolff Joc. cit.) : 
Annual and biennial plants. Perennial plants, 
Seeds - - 3 percent | Seeds - - - 8 per cent 
Stems - - - -5 “ “ | Wood- - - -1 “ & 
Roots - - - 4 “ “ {Bark - - - 7 % & 
Leaves- - - 15 “ “ | Leaves - -10 “ & 
7 
