476 
Still, the formation in Goeree differs from that assumed by Massart ; 
archeological findings below the layers of sand proved that they 
must have been deposited there later than + 200 A. D.'), and 
probably they are an aeolian formation from more westerly and 
lixiviated older dunes, in the manner advocated by Jrswrer (I.c.) with 
regard to the grounds north of the Meuse. It appears, indeed, that 
their calcium-content does not increase even down to a rather great 
depth (+ 1 m.); and amounts in the Oude Land van Diepenhorst 
only to 0,018°/, CaCO,. I will not enlarge upon the matter, but 
will only add that the calcium-content in the Oude Land van Die- 
penhorst, is lowest (less than, 0,02 °/,)*); in the Western-, and the 
Central-dunes slightly higher (+ 0,1 °/,), while towards the coast it 
rises to + 1°/,. Now, while the grounds of the inland-dunes con- 
sist entirely of sand, and possess a psammitic flora in the sense of 
Drnde, the vegetation of the meadows in the Land van Diepenhorst 
is of quite a different nature from that of the ‘“Meent’’-meadows in 
the Western- and the Central-dunes. In the former we find every- 
where Sarothamnus vulgaris and occasionally Erica tetralix and Cal- 
luna vulgaris; in the latter all three are absent. This difference 
cannot be referred to the meadows being fed down, or to more or 
less manuring by the grazing cattle, these factors being the same 
for either territory; so we may readily correlate this difference in 
flora with the greater or smaller calcium-content of the soil, since 
the broom as well as leather and erica are considered to be calcifuge. 
The problem of calcifuge and calcicole plants is an intricate one 
and not by far solved; consequently it has given rise to an 
extensive literature, of which only the principal points can be dealt 
with in the present paper. In our case, however, there is the ad- 
vantage, that some factors, which in other cases are of vital im- 
portance, may be readily eliminated here. This refers especially to 
the physical factors, such as structure of the soil, size of the grains 
and in this connection the aqueousness of the soil, and the sensiti- 
vity to the sun’s rays. 
Researches by Tuurman’), and afterwards by Gr. Kraus*) have 
pointed out the great significance of these factors, especially. for 
1) | feel greatly indebted to Prof. Horwerpa for imparting to me the age of 
the objects found. 
9) Our method of determining Ca was the same as that used by Jeswiet (Lc). 
We confined ourselves to determining only the content of the Ca-compounds that 
could easily be attacked, i.e of those which are of interest for plant-food. 
3) THuRMAN, Essai de phytostatique appliqué à la chaîne du Jura. 1849. 
4) Gr. Kraus, Boden und Klima auf kleinstem Raum. 1911. 
