486 

type of contaminated rock and certain xenoliths 
extremely rich in magnesia and lime. The modified 
xenoliths sink in the acidified magma of the con- 
taminated zone; they pass into the underlying 
sheet of initial gabbro, which becomes enriched in 
magnesia and lime, with the formation of the norite 
now seen beneath the contaminated zone. The 
chemical variation in the contamination-process is 
exactly the same as that in igneous rocks as a whole. 
Reciprocal reaction may play a part in magmatic 
differentiation, especially in the great gabbro-sheets. 
Mineralogical Society, March 13.—Dr. A. Hutchinson, 
president, in the chair—aA. Hutchinson: A graphical 
method ot correcting specific gravity determinations. 
A diagram is given by which the correction for air 
displacement and reduction to 4° C. can be read off 
directly —A. Brammall and H. F. Harwood: The 
Dartmoor granite (Widecombe area). Field evidence 
and analyses support the conclusion that the granite 
is a composite laccolite and that four successive 
stages of intrusion are recorded by (1) dark and 
relatively basic granites scantily exposed and by 
certain cognate xenoliths resembling basic segrega- 
tions ; (2) a more acid granite which caps many tors 
and yields mineral evidence of having assimilated 
country rock; (3) a still more acid granite intrusive 
into the latter ; (4) minor acid intrusions. Felspars, 
garnet, cordierite, etc. are desciibed, and evidence 
for differentiation is given.—-C. E. Tilley: Genesis 
of rhombic pyroxene in thermal metamorphism ; 
mineral associations and the phase rule. Free-silica 
hypersthene-bearing hornfelses of sedimentary origin 
can be divided into a calcic and non-calcic group, and 
considered as derived from a normal shale hornfels 
by increments either of CaO, (MgO +FeO), or less 
commonly K,O. Silica-poor hypersthene hornfelses 
can be derived from the free-silica types, and the 
hypersthene is then frequently accompanied by spinel. 
The derivation of all these hornfelses can be graphic- 
ally expressed in systems of three or four components. 
The hypersthene is derived from the chlorite in the 
original sedimentary rocks subjected to metamorph- 
ism. Hypersthene arises when enstatite, augite, 
or amphibole-bearing igneous rocks enter contact 
aureoles. Rhombic pyroxene is produced by con- 
tamination of gabbroic rocks.—C. S. Garnett: (1) On 
a peculiar chlorite-rock at Ible, Derbyshire. A band 
in the dolerite sill at Ible is completely altered to a 
foliated mass of chlorite, with associated veins of 
fibrous chlorite (resembling chrysotile in appearance). 
The analyses and characters of this material are 
compared with those of ‘‘ epichlorite.’’ (2) The dis- 
sociation of dolomite. Dissociation is inappreciable 
up to 625°, and at 898° it is complete. The tempera- 
ture-dissociation curve is continuous.—J. G. C. 
Leech: Occurrences of rutile, brookite, and anatase in 
the St. Austell granite. These minerals occur in the 
red pneumatolysed granites of the area, the mode of 
occurrence being essentially the same as that recorded 
for Dartmoor occurrences of these minerals. 
Linnean Society, March 15.—Dr. A. Smith Wood- 
ward, president, in the chair—J. Parkin: The 
strobilus theory of Angiospermous descent. The 
idea that the flower has evolved by reduction from a 
bisexual cone of a special type is elaborated. This 
Anthostrobilus is characterised by having the micro- 
sporophylls borne on the axis invariably below the 
- megasporophylls ; it is peculiar to the Angiosperms, 
Bennettitales, and Gnetales. From the Pterido- 
sperms, strobilate plants arose either (1) by the 
segregation of the two kinds of sporophylls into 
unisexual cones, or (2) by their aggregation into one 
and the same cone. The Anthostrobilus may have 
NO. 2788, VOL. 111 | 
NATURE 



[APRIL 7, 1923 
been called into being through the substitution of 
insect-pollination for wind-pollination. The Angio- 
sperms are regarded as a monophyletic group and 
the Monocotyledons as of monophyletic origin from 
the Dicotyledons and of Ranalian extraction. The 
8-nucleate sac is taken as primitive for Angiosperms. 
A return to the Ranales as the starting-point for the 
evolutionary study of the flower is advocated. 
Aristotelian Society, March 19.—Prof. A. N. White- 
head, president, in the chair—Miss H. D. Oakeley : 
Prof. Wildon Carr’s Theory of Monads. The import- 
ance as well as the difficulties of this theory lie in its 
attempt to combine into a unity the points of view~ 
of idealism and of creative evolution. The means by 
which the two viewpoints are brought into unity is 
the concept of reality as activity. The theory raises 
complex and many-sided problems in regard to a 
monad’s knowledge, the aature of the material world, 
inter-monadic intercourse and the ultimate reality 
within or beyond experience. The problem of know- 
ledge is conceived by Prof. Carr from the point of 
view of relativity and the doctrine of perspectives. 
The material universe results from the dichotomy of 
experience essential to activity, for activity can be 
conceived only as an opposition of antithetical 
forces. ‘‘ Activity’ is the core of the metaphysical 
theory. It is the reality of the monad, and its first 
expression is the esthetic creative production of 
images. The doctrine of the monadic nature of 
reality is based on intuition, but Prof. Carr claims 
that modern science confirms his view, arguing that 
science must postulate that monads constitute the 
real, in order to make its results fully intelligible. 
Knowledge according to the theory must be perspec- 
tive in form, and this also is supported by arguments 
from modern scientific relativity. 
Royal Microscopical Society, March 21.—Prof- 
F. J. Cheshire, president, in the chair.—M. T. Denne: 
An improved apparatus for the production of photo- 
micrographs, The apparatus consists of a bed made 
up of two heavy rectangular metal bars, upon which 
slides a carriage, one end of which is shaped to act 
as support for the microscope lens system, a separate 
microscope not being used. The carriage also bears 
one end of the camera bellows, and an optical bench 
for the below-stage apparatus. The head of the 
camera with dark slide fitting is fixed at one extremity 
of the bed itself. The eyepiece of the microscope 
is brought through the orifice of the plate-holder 
fitting, when adjustments may be made, the camera 
bellows being collapsed over the body of the micro- 
scope. For metallurgical work the usual vertical 
illuminator is employed with a right-angle prism 
arranged above the main optical axis. The apparatus 
is compact, although giving 800 mm. camera exten- 
sion, and, since it is not necessary to swing the 
microscope out of the axis for preliminary adjust- 
ments, difficulties due to decentralisation are 
eliminated.—A. C. Thaysen and H. Bunker : 
The destruction of cellulose fibres and fabrics by 
micro-organisms and the importance of the micro- 
scope in the study of this destruction. Destruction 
of fibres such as cotton and flax involves vast sums 
of money; the United States Department of Agri- 
culture place the annual damage to American cotton, 
on this account, at seventy million dollars. Different 
types of cotton are differently affected. All true 
Indian cottons appear to deteriorate quickly, at a — 
rate which is constant. American cottons are far 
more resistant, but they also show a constancy in 
their rate of deterioration. The greater resistance 
of American cottons appears to be due to at least 
two factors: the absence of food, and some more 

