eee Ty —« 
APRIL 25, 1912] 
serves. The author of the present volume set out 
to remedy this deficiency by making adequate 
study of a little region near Karlstadt-on-the-Main, 
where the sandstone with its green woods and 
red, moist soil gives place to limestone and a dry, 
glistening white soil. 
In similar instances it has been the practice to 
attribute the difference of flora to the presence of 
calcium carbonate in the limestone soil and its 
absence from the sandy soil, and the author began 
with this hypothesis in view by making numerous 
determinations of calcium carbonate in the soil. 
But he was soon driven to the conclusion that 
calcium carbonate is an exceedingly variable 
quantity; indeed, he doubts whether any esti- 
mate can be obtained of the amount in the 
layers of the soil immediately in contact with the 
plant root. 
cepted way, however, and comparing the analytical 
results with the vegetation, he failed to find any 
plant that occurred exclusively on soils of even 
approximately the same calcium carbonate con- 
tent; there were always variations within very 
wide limits. A vague relationship unly could be 
traced: some plants showed a clear preference for 
soils containing a high amount of calcium car- 
bonate, whilst others were found on soils containing 
only small quantities. Thus Festuca glauca 
occurred on soils containing 28 to 64 per cent., 
Teucr:um montanuni on soils containing 11 to 73 
per cent.—more generally, however, when more 
than 35 per cent. was present—and Melica ciliata 
where 24 to 60 per cent. occurred. Against these 
the limits for Brachypodium pinnatum were 2 to 
43 per cent., for Koeleria cristata 1'4 to 27 per 
cent., and for Hieracium pilosella 16 to 56 per cent. 
A mixed flora was found where the limestone 
merged into the sandstone. True chalk plants 
like Pulsatilla and Hippocrepis grew in spots where 
calcium carbonate was absent, while calcifugous 
plants like Calluna and Vaccinium were found in 
places where more than 3 per cent. of calcium car- 
bonate occurred, and alongside Anemone sylvestris 
flourished. With the exception of a few plants 
that require large amounts of calcium carbonate 
the author seems to have found most of the local 
ealcicolous plants on soils entirely free from cal- 
cium carbonate. 
the lime content of the soil as a true basis of dis- 
crimination, and looks forward to the time when 
every calcicolous plant shall have been found on 
chalk-free soils. 
The wandering of plants for which cal- 
cium carbonate is supposed to be essential on 
to chalk-free soils has been already observed, but 
never accounted for. When exceptions to a rule 
Making the determination in the ac- | 
He has completely lost faith in | 
NATURE 
187 
invent a new name to describe the exceptional case 
and after a while to take the name as an explana- 
tion of the phenomenon, and the cynic might argue 
that something of the sort has happened with the 
word invented in this instance—heterotopism. The 
present author, however, goes further; since the 
calcium carbonate hypothesis fails, he turns to a 
second hypothesis, the view that the physical pro- 
perties of the soil and not the calcium carbonate 
really determine the distribution of plants. The 
particular set of properties best suited to calcicolous 
plants are usually found in soils rich in calcium 
carbonate, while those suited to calcifugous plants 
are associated with soils poor in calcium carbonate ; 
but the carbonate itself does not play the control- 
ling part in the matter. The author is not prepared 
to say that calcium carbonate exerts no specific 
action on the plant, but he knows of no proof that 
it does. Even small quantities of calcium carbonate 
| are known to affect markedly the properties of the 
soil; he therefore made mechanical analyses, deter- 
mined water-contents and temperatures of the soils, 
and also noted their aspects and general relation 
to their surroundings. Working over very small 
areas in great detail, he finds distinct similarity in 
general physical conditions on spots where the 
same plants are growing. In the last instance the 
physical properties of the soil are some function of 
the soil structure, which therefore he considers to 
be the determining factor. 
Whether the author’s conclusions are wholly 
justified can only be ascertained by further experi- 
ments, but he certainly makes out a strong case for 
his main thesis that the botanist must pay more 
attention to the properties of the soil if he wishes 
to account for the distribution of plants. The book 
will be found of much interest to ecologists as a 
piece of painstaking and methodical work, and 
it emphasises the important fact that careful in- 
vestigation over a limited area is likely to prove 
very fruitful in the study of ecology. 
E. J. Russet. 
THE ADVANCE OF PHOTOGRAPHY. 
The Advance of Photography: its History and 
Modern Applications. By A. E. Garrett. Pp. 
xiii+ 382. (London: Kegan Paul, Trench, 
Triibner and Co., Ltd., 19rz.) Price 12s. 6d. 
net. 
T is about forty years since Dr. Hermann 
if Vogel wrote his volume entitled ‘‘ The 
Chemistry of Light and Photography in their 
Application to Art, Science, and Industry ” for the 
“Tnternational Scientific Series,” so well known 
by their red covers. The copy before us is a “new 
and revised” edition issued in 1876, and about 
begin to crop up, there is a strong temptation to } two-fifths of its contents are devoted to historical 
NO. 2217, VOL. 89| 
