ad 
NATURE 
[January 8, 1914 _ 
of the brothers Rogers in the Appulachian moun- 
tains of the United States. Ihe great majority 
cf the ‘“‘defermation mountains” are shown to be 
undoubtedly “folded mountains,” and, as may be 
expected in a work of this kind, the important 
light thrown u,.: “:0umtain-origin by the study 
of the Scottish Highlands, as a mountain chain 
dissected by denudation, is admirably explained, 
though we miss any reference to the value of the 
!atours ef Nicol and Lapworth in this connection. 
‘he varieties of folding and the relations between 
‘siding and “thrusts” find full illustration; and 
the theoretical views of Heim, Steinmann, Suess, 
and other continental authors on the nature, 
extent, and results of the great complexities ex- | 
hibited in the Alps, with their possible causes, 
are fairly stated though not fully discussed. The 
influence of jointing and weathering in producing 
the various types of alpine scenery rightly occupies 
a very important place in the work. 
A second class of ‘dislocation mountains ” in- 
cludes curious types recognised in recent years 
by the geologists of the United States, with the 
‘“horsts”” of German geologists. In all of these, 
extensive faulting—like that by which the moun- 
tains of Moab are left in relief by the great Dead- 
Sea fault—has been the chief agency concerned 
in their formation. 
The mountains carved by denudation out of 
great igneous masses (the so-called “laccolites ” 
and “batholites”) constitute the author’s third 
class of “deformation mountains,” and are illus- 
trated by the Henry mountains of North America 
and the Red Hills and Coolin Hills of Skye. It 
is here that we detect a little want of consistency 
in the classification adopted by the author. In 
describing his volcanic mountains he rightly refers 
not only to the denuded remains of small cones— 
commonly called “necks’’—but to masses of lava, 
like the North Berwick Law, or of lava and tuffs 
like Largo Law, which are so conspicuous in the 
Scottish Lowlands as forming the denuded cones 
of great volcanoes. But the similar masses in 
Skye and the other islands of the Inner Hebrides 
do not differ from these in anything but their 
greater dimensions, and it seems scarcely justifi- 
able to place them in a totally different class. 
The final chapter of the book is devoted to the 
examples which the older geologists styled 
“mountains of circumdenudation,” but which the 
author designates ‘subsequent or relict” moun- 
tains, of which we have such striking British 
examples in the great stacks of Torridon sand- 
stone in western Sutherland and Ross. 
Not less instructive than the text of this excel- 
lent work is the selection of eighty photographic 
plates which illustrate it. One-half of these is 
taken from the admirable series prepared by the 
Geological Survey of Scotland, and they show 
how rich our country is of examples of mountain 
structure; the other half consists of pictures 
supplied by photographers of Switzerland and the 
United States. 
: Je Wag, 
NO. 2306, VOL. 92] 
ZONAL STRUCTURE IN 
ANIMALS.1 
Re 
5 Veo a drop of strong silver nitrate is 
placed on a thin layer of 5-10 per cent. 
gelatine containing about o'r per cent. of potass- 
ium bichromate, remarkable phenomena are 
observed. The gelatine under the drop is coloured 
red-brown by the abundant precipitation of silver 
chromate. The nitrate spreads gradually by 
diffusion into the gelatine, the rusty brown area of 
precipitation enlarges, it forms at its periphery a 
dull whitish seam, and further outwards in the 
gelatine a system of numerous concentric rings 
is developed, spreading like rings on the surface 
of a quiet pool. These are the well-known Liese- 
gang’s rings or zones, and the central idea of 
Prof. Kiister’s investigation is that these throw 
light on zoned structure in cells and tissues. He 
has made numerous experiments with the diffu- 
sion zones formed in colloidal media in vitro, and 
he seeks to utilise the phenomena observed in the 
interpretation of organic structures—such as 
cross-striping in leaves, annular and other mark- 
ings in cells and vessels, the layers in starch- 
grains, the markings on diatoms, the lines on 
butterflies’ wings, on shells, on feathers, on por- 
cupines’ quills, and what not. 
Ostwald’s explanation of Liesegang’s rings is 
not unanimously accepted, but no one doubts that 
the phenomenon will be cleared up in terms of — 
laws of diffusion, concentration, precipitation, and 
the like. Prof. Kiister does not go into that; his 
object is to make zoned structure in organisms 
more intelligible by bringing it into line with 
Liesegang’s rings. He is aware of the risks of 
arguing from the conditions of inorganic processes 
to those of organic processes, of mistaking simi-— 
larity for sameness—and he quotes the wise ad- 
vice that Roux has given in connection with this 
kind of argument. 
Prof. Kiister admits that his suggestion is only — 
at the stage of hypothesis, for we do not know 
much about the active substances the diffusion of 
which in cells may induce zoned structure. We 
cannot isolate them and experiment with them. On 
the other hand, Prof. Kiister points out that organ- 
isms are largely built up of colloid material, and 
that his experiments in vitro were with colloidal 
material, that artificially induced modifications of 
Liesegang’s rings find their parallel in organic 
structure, and that the zoned structure occurs in — 
the most diverse kinds of plants. His experi- 
ments show that “rhythmic structure may arise 
without any rhythmic influence from the outer 
world, and that even simple diffusion processes 
can give rise to rhythmic structures.” Is it not 
probable that analogous occurrences take place in 
the formation of zoned organic structure? It may 
be said that in living creatures the rhythms are 
characteristically dynamic, but our author replies — 
to this by referring to Bredig’s “pulsating 
1 ‘Ueber Zonenbildung in kolloidalen Medien.” By Prof. Ernst Kiister, 
Pp. r11+53 figs. (Jena: Gustav Fischer, 1913.) Price 4 marks, 
PLANTS AND 
