430 
NATTA 
[FEBRUARY 28, 1907 
sequently been advocated by Armstrong, Beilby, van Laar, 
and others. The simplest case of a semi-permeable mem- 
brane is undoubtedly to be found in the surface of separ- 
ation between liquid and vapour. At such a surface the 
kinetic theory postulates a continual interchange of mole- 
cules between the two phases. But whilst the rate of 
escape or evaporation would be reduced by the presence of 
non-volatile molecules in the surface, the rate of con- 
densation would be unaffected, and equilibriiim could only 
be restored by decreasing the vapour pressure, and so 
diminishing the rate of condensation at the surface of the 
solution. In this case a quantitative relationship could be 
deduced.—The bearing of actual osmotic experiments upon 
the conception of the nature of solutions: Prof. L. 
Kahlenberg. The occurrence of osmosis and its direc- 
tion and extent are determined by the nature of the 
septum and of the liquids that bathe it. Experiments have 
shown, too, that there is always a major and minor current 
present, following in opposite directions, although it often 
appears as if the osmotic process were one-sided. In this 
case the septum is termed ‘‘ semi-permeable,’’ and recent 
research has centred around so-called semi-permeable mem- 
branes which really do not exist. The author has demon- 
strated that it is peculiarly strong selective action on the 
part of the septum which causes it to be approximately 
semi-permeable in certain cases, and he has recently even 
succeeded in separating two colloidal substances by dialysis. 
This selective action is due to the solubility or insolubility 
of the substances concerned in the membrane, and there- 
fore osmotic pressure is due to the same forces—essentially 
chemical in character in the opinion of the author—as the 
process of solution, and they may be quite variable as 
different septa and different liquids are employed. The 
usually accepted ‘‘ sieve theory’’ is untenable, because 
larger molecules frequently go through a membrane more 
readily than smaller molecules. —Tables containing a sum- 
mary of the recent experiments made with glucose ‘and cane- 
sugar: H. N. Morse. The conclusions arrived at are : 
(1) In the vicinity of 20° the osmotic pressure exerted by 
either is equal to that which a molecular equivalent 
quantity of a gas would exert if its volume were reduced, 
at the same temperature, to the volume of the solvent in 
the pure state. (2) Between 18° and 26°, at which the 
measurements were made, both cane-sugar and glucose 
in solution are in the anhydrous condition. Measurements 
made just above o° yield pressures somewhat above the 
calculated gas pressures. Measurements with electrolytes 
are about to be made in which osmotic pressure and 
dissociation will be determined simultaneously. 
Entomological Society, February 6.—Mr. C. O. Water- 
house, president, in the chair.—Exhibitions.—E. A. 
Cockayne: A collection of Lepidoptera made at Tongue, 
North Sutherlandshire, between June 30 and July 13, 1906, 
comprising many species not hitherto reported from the 
county. The. several species showed little tendency to 
melanism.—Dr. T. A. Chapman: Specimens of Hastula 
hyerana, Mill., to demonstrate how it may vary towards 
melanism in the circumstances of late or retarded emer- 
gence.—Miss M. E. Fountaine: Examples of Anthocharid 
and Melitseid butterflies from various localities in the 
Palzaretic regions, showing a wide range of variation.— 
The President: A female example of the genus Dorylus 
from Mengo, in Uganda, and one small and two large 
workers, which would probably be the means of identify- 
ing the species. The workers closely resemble specimens 
in the museum named D. arcens, which are said to be 
the same as ntigricans.—Rey. F. E. Lowe: Various 
aberrant forms of Swiss butterflies, including Melanargia 
galatea, ab. fulvata, Lowe, from Martigny ; Lycaena arion, 
from Pontresina, with the black markings on the under- 
side of the wings almost entirely absent, save one very 
large kidney -shaped spot, slightly tinged with white at the 
centre of each wing; and_a pair of Pieris napi, var. 
bryoniae, taken in cop. at Caux, the ¢@ not only suffused 
as in bryoniae, but also having the Q markings.—Colonel 
Charles T. Bingham: The pupa of a Tineid ‘moth, prob- 
ably of the genus Brinsitta, from Upper Burmah, present- 
ing with its surroundings a remarkable mimetic resem- 
blance to the head and ‘body of a snake; and a case show- 
ing the curious habit of butterflies of the genera Gerydus 
NO. 1948, VOL. 75 | 
and Allotinus attending with ants on Aphidze for their 
sweet exudations.—Rev. F. D. Morice: A very remark- 
able gynandromorphous specimen, from Silchester, of the 
common fern-visiting sawfly, Strongylogaster cingulatus, 
the dividing line between the @G and the Q portions 
running longitudinally, not transversely, from end to end 
of the creature; a form probably unique.—Papers.—Notes 
on the Indo-Australian Papilionide: Percy I. Lathy. 
The hymenopterous parasites of Coleoptera: E. A. Elliott 
and Claude Morley. 
Geological Society, February 6.—Dr. J. E. Mair, F.R.S., 
vice-president, in the chair.—Note on the cervical "vertebra 
of Zeuglodon from the Barton Clay of Barton Cliff (Hamp- 
shire): Dr. C. W. Andrews. The author gives a brief 
description of a cervical vertebra from the “Barton Clay 
of Barton Cliff. It is referred provisionally to Zeuglodon 
wanklyni, a species described in 1876 by Prof. H. G. 
Seeley. The skull on which this description was founded 
is totally lost, so that this vertebra is the only bone of 
a Zeuglodon from the Barton Clay, and, with the possible 
exception of a vertebra from the Brockenhurst beds (which 
is the type of Balaenoptera juddi), the only one found in 
the British Isles that now exists.—The origin and age of 
the plateaus around Torquay: A. J. Jukes-Browne. The 
existence of high-level plains or plateaus near Torquay has 
long been known, but since Pengelly’s time little attention 
seems to have been paid to them. Pengelly believed that 
there were several such plains at different levels, and 
thought that the time of their production was not very 
remote. On examination, however, his evidence breaks 
down, and the author regards the plateaus as portions of 
one inclined plain. The age of the planation is shown to 
be post-Permian, by the fact that Permian breccia forms 
part of the plateau-surface at St. Marychurch. It is also 
probably post-Cretaceous, because Cretaceous planation is 
not likely to have removed all the Permian. Its present 
dissected condition shows that it is older than the Pleisto- 
cene, and consequently an Eocene date would agree with 
local evidence. 
Linnean Society, 
February 7.—Lieut -Colonel Prain, 
F.R.S., vice-president, in the chair.—Some observations of 
climbing plants: Rey. John Gerard, S.J. The author 
began by pointing out the two opposing methods of de- 
scribing spiral growth or torsion as viewed from the 
exterior or from the interior of the spiral, the result being 
that the ‘‘ dextrorse’’ of the first is the ‘‘ sinistrorse ’’ of 
the second method. With or against the sun, which applies 
to the northern hemisphere, is reversed in the southern 
hemisphere, and for these reasons he preferred to use the 
terms ‘‘ clockwise ’’ and ‘‘ counter-clockwise ’’ (shortened 
to ‘‘counterwise’’), the honeysuckle (Lontcera  Pericly- 
menum) and the hop (Humulus Lupulus) turning clock- 
wise, and the convolvulus (Convolvulus arvensis) and the 
searlet-runner bean (Phaseolus vulgaris) twining counter- 
wise. He showed the result of some experiments he had 
made by growing scarlet-runner beans in opaque cylinders, 
to discover, if possible, whether the deviation of the twist 
were innate, from the direction of the light, the con- 
“cc 
clusion being drawn that the plant possessed an inclin-— 
ation resembling the instinct of animals, of proceeding in a 
given direction, and resented any attempt to force it other- 
wise. The author concluded with 
the behaviour of tendrils, as those of Bryonia dioica, dis- 
playing one specimen which had varied the torsion four 
times, and showed ten turns in one direction against 
seventeen in the contrary.—New plants from Malaya: Dr. 
Otto Stapf. The author gave the history 
genus Hallieracantha, which receives eight species from 
the genus Ptyssiglottis, Hallier f., and eleven others are 
added from the Kew collections ; they form a very homo- 
geneous group, are eminently shade-loving plants, and 
exhibit anisophylly in a very marked degree. The head- 
quarters of the'genus are in Borneo.—Tertiary Foraminifera 
of Victoria. The Balcombian deposits of Port Phillip : 
F. Chapman. 
Physical Society, February 8.—Prof. J. Perry, F.R.S., 
president, in the chair.—Annual general meeting.— 
Presidential address: Prof. Perry. In concluding his 
address, Prof. Perry remarked that a 
i should know decimals at eight, he should use squared 
some observations on 
of his new | 
standard boy | 
