MarcH 31, 1904] 
habits of Xyleborus dispar, Fabr., by Dr. Thomas Algernon 
Chapman: G. C. Champion.—Further notes on 
Hydroptilida belonging to the European fauna, with de- 
scriptions of new species: K. J. Morton.—A note on 
Elymnias borniensis, Wallace: R. Shelford.—A discussion 
on ‘‘ What is a Species? ’’ was opened by the Rev. F. D. 
Morice, in which Mr. H. J. Elwes, Prof. F. A. Dixey, Mr. 
A. J. Chitty, Mr. W. E. Sharp, the president, and other 
fellows joined. 
Geological Society, March 9.—Dr. J. E. Mc F.RS., 
president, in the chair.—On the probable occurrence of an 
Eocene outlier off the Cornish Coast: Clement Reid, 
F.R.S., communicated by permission of the director of 
H.M. Geological Survey. The evidence suggests that, 
underlying the western part of the English Channel, an 
Eocene basin may occur comparable in importance with 
that of Hampshire.—The Valley of the Teign: A. J. Jukes- 
Browne. ‘The Teign Valley is not a transverse valley pre- 
serving a general direction in spite of opposing ridges, nor 
is it a longitudinal valley running parallel to a dominant 
ridge, nor is it a simple combination of one with the other, 
as often happens; but it apparently consists of parts of 
two transverse valleys linked by a longitudinal one. The 
Teign runs off Dartmoor through a gorge which takes an 
easterly direction, as if it were going to join the Exe; it 
is then deflected southward into what, with respect to the 
Permian escarpment, is a longitudinal valley; this ends 
in a low-lying plain, and from this plain it escapes eastward 
to the sea through a transverse valley, which has been cut 
across the ridge of Permian and Cretaceous rocks. The 
theory of the capture of one river by another furnishes an 
intelligible explanation of the facts when applied to the 
course of the Teign. The author thinks that some other 
river-courses and geographical features in Devon can be 
explained on the theory of an easterly incline modified by 
a subsequent southerly tilt. 
Physical Society, March 11.—Dr. R. T. Glazebrook, 
F.R.S., president, in the chair.—The whirling and trans- 
verse vibrations of shafts: Dr. Chree. The paper shows 
how the mathematical results obtained by Prof. Dunkerley 
can be derived by a less cumbrous treatment, and how in 
many instances they admit of great simplification, without 
sensible loss of accuracy. It is also shown how loaded 
shafts can be dealt with, without recourse to the hypothesis 
presented by Dunkerley; at the same time some light is 
thrown on the relation of this hypothesis to theory. Six 
main cases are considered, in which the shaft is variously 
supported ; in some of them numerical results are deduced 
for comparison with Dunkerley’s experiments.—Notes on 
non-homocentric pencils, and the shadows produced by 
them, part ii., shadows produced by axially symmetrical 
pencils possessing spherical aberration: W. Bennett. This 
paper deals with the shadows obtained by interposing a 
straight wire near the focus of a pencil proceeding from a 
lens or mirror uncorrected for spherical aberration. A 
method is described for drawing sections of the wave-front 
in the neighbourhood of the focus. A simple physical ex- 
planation of the shadows is given by means of the wave- 
fronts; it is shown that the real shadow consists in general 
of two branches, one closed and the other open, with a 
¢-form as a symmetrical special case. The equations of 
the wave-front are worked out for the special case of the 
reflection of a plane wave at a spherical mirror, and a 
method of drawing the shadow-forms is described. 
Linnean Society, March 17.—Prof. J. Bretland Farmer, 
F.R.S., vice-president, in the chair.—An account of the 
Bryozoa from Franz-Josef Land, collected by the Jackson- 
Harmsworth Expedition, 1896, 1897 (part ii., Cyclostomata, 
Ctenostomata, and Endoprocta): A. W. Waters. Mr. 
Waters comments on the confusion that has arisen from 
attempts to base a classification of the Cyclostomata on 
almost valueless characters taken from fossils. The bipolar 
theory of distribution, in his opinion, receives little support 
from the Bryozoa, in several instances species that are dis- 
tinct having been united, and in the comparison of opposite 
areas the terms Arctic and Antarctic not having been used 
with similar strictness.—Botanic illustration from the 
fifteenth to the twentieth centuries: B. Daydon Jackson. | 
NO. 1796, VOL. 69} 
NATURE 
527 
CAMBRIDGE. 
Philosophical Society, February 29.—Dr. Baker, presi- 
dent, in the chair.—On decomposition of hydrogen dioxide 
under the influence of radium bromide: H. J. H. Fenton. 
These experiments were originally undertaken with the 
object of studying the conditions of stability in aqueous 
solutions of pure hydrogen dioxide at the ordinary tempera- 
ture in absence of light. The observations have been ex- 
tended so as to include an investigation of the influence 
exerted by rays from the latter substance on the decom- 
position of the dioxide. It has been shown by Bredig and 
his colleagues that the rate of decomposition of hydrogen 
dioxide under the influence of catalysers, such as colloidal 
platinum, and in presence of many electrolytes and non- 
electrolytes, follows the law for a reaction of the first order ; 
in the case of the pure dioxide alone, however, under the 
influence of platinum, the change is not strictly in accord- 
ance with this law, the value of the constant increasing as 
the concentration of the dioxide becomes smaller. Similar 
results are obtained in the present instance when the 
aqueous solution undergoes decomposition either alone or 
under the influence of radium rays. In the latter case, how- 
ever, the change is greatly accelerated, the value of the 
constant in each case being approximately double that 
calculated from the parallel blank experiment. Further ex- 
periments are in progress with the object of ascertaining 
whether the oxidation of organic substances, either alone or 
in presence of iron, is influenced by radium.—Exhibition of 
oribatid mites taken in the neighbourhood of Cambridge : 
C. Warburton and N. D. F. Pearce. The Acari have 
received little attention in this country, and this is the first 
attempt to investigate the local fauna of any acarine group. 
In four winter months specimens of forty-seven out of the 
hundred known British species have been taken in the 
neighbourhood of Cambridge, and every one of the fifteen 
British genera is locally represented.—Some observations on 
the determination of sex in plants: R. P. Gregory. The 
work was carried on in response to Castle’s suggestion 
that sex may be a character inherited in accordance with 
the Mendelian principles of segregation and dominance. 
The problem is rendered more complex in plants owing to 
the occurrence of two distinct generations (the sporophyte 
and the gametophyte) which regularly alternate in the life- 
history of the plant. In the flowering plants the alternation 
is masked by the complete dependence of the gametophyte 
upon the sporophyte; but in the ferns this is not the case; 
this group was therefore chosen as the subject for investi- 
gation. From the observations it appears that sex in the 
sporophyte is homologous with that in animals, and may 
perhaps be inherited in accordance with Mendelian prin- 
ciples. It is to be distinguished from sex (as manifested 
by the production of antherozoids or of ova) in the gameto- 
phyte, the latter being determined by the conditions of 
nutrition.—On variation in the number and arrangement of 
the male genital apertures, and on the relative proportion 
of the sexes, in the Norway lobster (Nephrops norvegicus) : 
D. C. Mcintosh. The results are given of an examination 
of 656 specimens obtained from the Firth of Clyde. The 
percentage having an abnormal number of genital apertures 
Was 2-49, or considerably lower than that recorded by 
Marshall for the Norway lobsters from the Firth of Forth. 
Among the Clyde specimens the sexes occurred in approxi- 
mately equal proportions, the females on an average being 
ot considerably smaller size than the males.—On the boiling 
points of homologous compounds: H. Ramage. The re- 
lation of boiling point to molecular weight has been studied 
by means of diagrams drawn with the former as abscissze 
and the latter as ordinates. These indicate that Walker’s 
formula for the ten paraffins C,H,, to C,,H,, only applies 
to the CH, linkage in the molecules, and that the influence 
of the terminal hydrogen atoms is either a constant in these 
higher members of the series or it is so small it may be 
disregarded. The influence of the terminal atoms increases 
as the chain shortens, and Walker’s formula does not, on 
this account, apply to the lower members. This view has 
led to a modification which includes all the series up to 
C,,H,,. The new formula is T=a/M(1—2-”)}3, in which 
T is the boiling point in absolute degrees, a is a number de- 
pending on the pressure, M is the molecular weight, and 
n the number of carbon atoms in the molecule. 
