NUTRIENT SALTS. 69 
| Water-soldier. Water-lily. Stone-wort. Reed. | 
mn ee | 
FBO baSH sce ER! | 30°82 14-4 02 86 
NO cnc etates cone reac nose seaatas ans 2°7 29°66 O1 04 
1 Dp} Gas poccodeceBacosquC OnE AOCGOCOHECOOOC 10°7 18:9 54°8 59 
SINCICKACHd nennen ens 1'8 05 03 715 
The other constituents of the ash of these plants, in particular iron oxide, mag- 
nesia, and phosphoric and sulphuric acids, exhibited less marked differences; but 
the inequality in the amounts of potash, soda, lime and silicic acid are so great, 
as only to be explicable on the assumption of a power of selection on the part of 
these plants. Various species of brown and red sea-weeds, which had been attached 
to the same rock and developed in the same sea-water, showed similar variations 
in the composition of their ash. 
On the mountains of serpentine rock near Gurhof, in Lower Austria, specimens 
of Biscutella levigata and Dorycniwm decumbens were collected from plants 
growing together, and one above the other, upon a declivity which they clothed. 
Their roots, interlaced here and there, were fixed in the same ground, and drew 
nourishment from the same store. The following table gives the composition of 
the ash in these two species:— 
Biscutella Doryenium | Biscutella Doryenium | 
leyigata. decumbens. laevigata. decumbens. 
= 
Rotashteerceco.ceees 9:6 16°7 Silieie Acid,........... | 13:0 63 
JLT} en eeeeenaes 147 20:9 DUlDDUN ER ee | 52 1:6 
Magnesia,........... 28°0 19°6 Phosphorus,........... 159 22°3 
97 
Iron Oxide,......... 78 2:8 Carbonic Acid,....... | 54 
The differences here seem to be not so great as in the case of the water-plants 
previously given, but they are sufficient to prevent our regarding them as merely 
the result of chance. 
If, on the other hand, we compare the composition of the ash of different 
speeimens of the same species, which have been reared on similar soils, but at 
great distances from one another, the discrepancies are comparatively slight. 
Foliage from beech-trees growing on the limestone mountains near Regensburg 
yielded an ash practically identical with that obtained from leaves of beeches on 
the Bakonyer-Wald hills in Hungary. The ash of different individuals of a single 
species even exhibits the same constitution, in the main, when those individual 
plants have obtained their nutriment from soils differing greatly in chemical 
composition. Only in cases where the quantity of a substance in one soil is 
more abundant than in the other there is generally a greater or less amount of it 
to be found in the ash. 
That under these circumstances certain substances may replace one another is not 
improbable. But such substitution must be confined to those nearly allied com- 
pounds whose molecules are capable of being used indifferently by the formative 
