580 
NATLORE 
[Apriz 18, 1907 
morphological distinction so commonly insisted on as 
between axial and foliar structures is largely the 
result of preconceived views as to their essentially 
separate nature, or, as we would prefer to put it, of 
the general experience that they are distinguishable. 
But morphological differentiation is really not irrevo- 
cable. There many ways in which the normal 
(hereditarily transmitted) form may be changed if the 
sequence of those internal chemical changes that de- 
termine the structure at any given time and in any 
given instance can be interfered with, and this con- 
sideration should put us on our guard against the 
introduction of transcendental ideas into our morpho- 
logical conceptions. 
In the lower plants, in which the sequence of struc- 
tural change has remained less stereotyped, it is 
sometimes easy to control the course of development, 
and, within limits, to induce considerable modifi- 
cations in organisation. As an illustration we may 
recall the well-known case of the influence of light 
in determining the dorsiventrality of Marchantia. 
This plant produces lens-shaped brood bodies or 
gemmze, and when these are allowed to germinate, 
the surface (whether upper or lower), which is illu- 
minated, assumes the structure of the normally 
dorsal, the less, or non-illuminated, surface that of 
the ventral aspect. The behaviour under experi- 
mental conditions of Aneura ambrosioides, 
liverwort, may also be quoted. This plant forms 
beautiful tufts or sheets of pinnate thalli spread over 
the surface of the wet rocks or banks on which it 
occurs. But by appropriate methods of cultivation 
the plants can be made to grow erect, and then the 
ends of some of the pinnaz turn downwards to grow 
and ramify in the soil. The change thus induced is 
not necessarily permanent, and a restoration of the 
normal environment at once causes further growth 
to advance along the previous lines. But the interest 
attaching to such an experiment is enhanced when 
it is known that there are other nearly allied species 
the response of which to the influence of the ordinary 
environment takes precisely that form assumed by 
A. ambrosioides as the result of the introduction of 
certain special conditions. Many other examples of 
a similar kind will occur to those who are familiar 
with the results of the so-called ‘‘ experimental 
morphology.”’ 
In the higher plants a certain degree of latitude 
of organisation is generally recognised, but its limits 
do not, as a rule, exceed the chief morphological 
barriers. The genus Utricularia, however, stands out 
amongst the flowering plants as one that has pre- 
eminently broken loose from the trammels of 
hereditary tradition. The chain of events which in 
the vast majority of plants are linked together in a 
sequence so orderly that the final result—differenti- 
ation into stem and leaf—seems invested almost with 
the sanctity of a law of nature is here rudely inter- 
rupted. It is to this very circumstance that the 
Utricularias owe their great importance from the 
biological standpoint, and any contribution to our 
knowledge of the group is assured of an attentive 
reception. J. BacB: 
NO. 1955, VOL. 75] 
are 
another ; 
A NEW ATLAS, 
The M.P. Atlas. A Collection of Maps showing the 
Commercial and Political Interests of the British 
Isles and Empire throughout the World. Forty 
plates. (Edinburgh and London: W. and A. K. 
Johnston, Ltd., 1907.) Price net. 
255. 
HIS atlas consists of a series of maps chiefly 
representing the British Empire. They are 
very clearly printed, and some of them are de- 
cidedly good specimens of cartography. 
orographical map of 
The bathy- 
the British Isles is particu- 
larly worthy of notice. It is beautifully clear, and 
in every way excellent piece of work. The 
special feature of this map is the orographical colour- 
ing, the effect of vertical relief being obtained by 
means of a system of colour-tinting in shades of 
brown, the shades increasing in density with the 
elevation. The bathymetrical colouring is in shades 
of blue. As this is such an effective map, it is a pity 
the same scheme of colouring was not adopted for 
the other physical maps, as in comparison they, and 
particularly that of India, are much inferior produc- 
tions. 
Throughout the atlas there is, unfortunately, a lack 
of uniformity in the style and execution of the maps 
which detracts in no small degree from their artistic 
merit. The collection is composed of engraved and 
lithographed maps, and the contrast between the fine- 
ness of the former and the coarser work of the latter 
is in many instances very pronounced, more especially 
when examples of the two styles occur on the same 
sheet, as on Plate This variety in the method 
of production and certain inconsistencies which 
are to be found in the maps make it quite obvious 
that they have not been drawn specially for this atlas, 
but collected from various sources. There would be 
nothing to say against this system of using the same 
maps for different atlases, provided, of course, that 
they have been completely revised and brought up to 
the date of publication. But there is a great objection 
to the inclusion of old, or only partially revised, maps 
in a new atlas, and there are not a few in the ‘‘ M.P. 
Atlas.” 
Quite a large number of the maps have already 
appeared in other atlases published by Messrs. 
W. and A. K. Johnston, most of them in the 
well-known ‘‘ Royal Atlas,’’ and many require much 
more thorough revision to bring them up to the date 
on the title-page. For instance, on the map of Asia 
(Plate 20), the physical features are shown exactly 
as in the same map in an edition of the “ Royal 
Atlas’ published fourteen years ago, notwithstanding 
the considerable alterations and additions recent ex- 
ploration has made necessary. Then, again, there are 
railways and political boundaries that require correc- 
tion. With regard to the latter, attention may be 
directed to a discrepancy between the boundary of 
northern Nigeria as shown on the general map of 
Africa (Plate 29) and on the map of the West African 
colonies (Plate 34). But no doubt these matters will 
receive the publishers’ attention in revising the atlas 
for a future edition. 
an 
36. 
