174 T HE FAUNA AND FLORA OF FLORDON COMMON. 
pression at the end of a small pool showed io inches of surface 
soil, then very white calcareous soil six inches thick, and 
beneath that brown, with shells and much vegetable matter. 
The alluvium of the western common gave three feet of 
surface soil without the characteristic calcareous matter. 
The subsoil of the marsh under a very compact herbage, is 
generally firm, but in a few places a pole penetrated four feet 
of ooze, as it did in the channel of the old ditch. 
Analyses of five examples of the calcareous soil found by 
excavation in the marsh gave the following results : 
A B C D E 
Soluble in dilute Hydro- 
chloric Acid 
•843 
•732 
•897 
•637 
•789 
Combustible 
Ash insoluble in dilute 
•141 
•252 
•091 
•312 
• 180 
Hydrochloric Acid 
•016 
•016 
•on 
•025 
•031 
These figures show that in the five samples an average of 
78 per cent, was soluble in dilute hydrochloric acid, 20 per 
cent, was combustible, and there was a residue of 2 per cent, 
insoluble, the first indicating the soluble alkalies and alkaline 
earths, the second the carbonaceous matter, and the third 
insoluble ash containing silt, and compounds of silica, sulphur, 
iron and phosphorus from the plant debris. An examination 
of the figures, with the entire absence of stones, appears to 
indicate that the subsoil is the product of vegetable decom- 
position, and the action of living organisms on calcareous 
water. The small proportion of insoluble ash shows that 
alluvial matter is not brought in any quantity by flood- 
water from higher levels, yet the accumulation of ooze is 
visible in the deposit of calcium salts on vegetation in the 
pools. Tests of the hardness of the water made by soap 
soloids gave three to four degrees of hardness from springs, 
pools and stream, compared with an average of 12 to 20 
degrees in Norfolk waters. It is therefore obvious that 
plants can utilise infinitesimal quantities of salt in solution, 
a. fact of which Kerner gives some striking examples. The 
very low ash values of samples A and B may be due to the 
