136 W. B. Crump 
Deschampsia Jlexuosa, dominant on grit boulders and growing 
in fine sandy humus, Yorks., August, 1911. 
Air-dry Soil. Water. 
Water. Humus. Humus. 
170. At 2-4 ins. 33-3% 44-0% 0-75 
172. At 3-4 ins. 24-8 25-3 0-98 
Brotnus giganteus, in sandy alluvium on edge of a stream, 
Yorks., August, 1911. 
Air-dry Soil. Water. 
Water. Humus. Humus. 
173 i. Humus in ball of roots... 125'0% 25-4% 4-9 
ii. Stiff sand below ... 29’1 5-3 5-4 
Though the water-content of 173 ii. lies midway between that 
of 170 and 172 the coefficient separates the two habitats in the 
clearest possible way. The woods characterised by stretches of 
Deschampsia Jlexuosa were first distinguished as “Dry Oak Woods” 
in the Flora of Halifax. The distinction was then based upon the 
nature of the vegetation, but it is now confirmed by analysis 
of the soil. 
The Calcareous Formation. Through lack of opportunity cal¬ 
careous soils have not, as yet, received much attention, and it is not 
safe to draw comparative inferences from a limited number of 
samples, all taken under the exceptional conditions of the summer 
of 1911. But the utility of the coefficient of humidity is still 
apparent. 
Calcareous Grassland. 
Sesleria ccerulea , in crevices of limestone rocks, North Lancs. 
Air-dry Soil. Water. 
Water. Humus. Humus. 
132. April, 1911 . 31-4% 37-7% 0-80 
135. „ „ . 15-4 170 0-90 
162. August, 1911 . 22-3 19-0 M7 
The values of the coefficient are quite consistent in spite of the 
difficulty of obtaining uniform samples from the pockets filled with 
limestone chips, wildest the roots penetrate far into the crevices. 
The slightly higher value in August, in spite of the long drought, is 
of no importance. It merely indicates a local variation, a crevice 
more protected from evaporation. But it must he remembered that 
the Spring is often a season of drought. At the time when 132 and 
135 were taken there had been practically no rain for six weeks. 
So the analyses point rather to uniform conditions and a low 
humidity in these limestone crevices. 
