EFFECTS OF SOIL AND CULTIVATION ON PLANTS. 
215 
crops, and the soil best adapted should contain a proper proportion of silica, 
alumina, and lime, which seems to me can only be determined experimentally 
for each crop. 
The finest specimens of camomile flowers are obtained by carefully laying 
out the plants in rows, not nearer to each other, on any side, than two feet. 
By allowing sufficient space, growers compensate for such plants which re-^ 
(juire a more exposed position than can be obtained in the general way of 
cultivation. 
The tendency which some growers have of planting closely may explain 
the differences which have been observed in the medicinal effects of some 
plants, as foxglove and henbane. It is highly probable that growers have 
been stimulated to this practice by competitive impulse. 
It' is well known that plants which are secluded from light cannot perfect 
their seeds, nor effect the deoxidation of carbonic acid. As this results where 
the plants arc situated closely to each other, especially if they have large 
leaves, it is highly probable that species may be produced. This may serve 
to explain the° singular effect which I have already noticed in reference to 
henbane. 
Appendix. 
A. Analysis of Soil from a Wood near Wimbledon . 
Chlorides, magnesium and potassium ..... 2"1 
Sulphate of lime. '3 
Carbonate of lime... 
Carbonate of magnesia.1'1 
Oxide of iron and silica ......... 2 - 0 
Water (lost at 212°).12'0 
Organic matter. S3'0 
Loss. 
B. Analysis of Soil; vide page 213. 
Phosphate of lime, with traces of magnesia . . 
Chlorides of potassium and sodium . . . . 
Sulphate of lime.. 
Nitrate and phosphate of ammonia. 
Silica. 
Oxide of iron. 
Organic matter. 
Water . 
Less. 
100*0 
9-0 
4*6 
*5 
*7 
91 
11 
(13-3 
8*0 
3 7 
Analysis of Soil feom Mitcham. 
Crops raised: Lavender, etc. 1 ield of Oil per aci 
Carbonate and sulphate of lime. 
Carbonate of magnesia. 
Alumina. 
Silica. 
Oxide of iron. 
Phosphate of lime. # . 
Nitrate and phosphate of ammonia. 
Organic matter. 
Water (lost at 212° F.). 
Loss. 
100-0 
e, 8 lb. 
9-0 
3*8 
16-3 
20-5 
2-8 
6-0 
30 
23-7 
12-3 
2-6 
100-0 
