Marcu 5, 1914| 
February 19.—Prof E. B. Poulton, president, in the 
chair.—Dr. J. P. Lotsy: The origin of species by 
crossing. In all questions of evolution. facts are 
gathered from individuals, because species as well as 
varieties are abstractions, not realities. | Nobody is 
able to show a species or a variety; all he can do is to 
show one or more individuals which he believes to 
belong to the species or variety under discussion. Of 
individuals we know two kinds: homozygotes and 
heterozygotes. The first are stable, the latter segre- 
gate, earlier or later, into new homozygotes. The 
offspring of a homozygote is identical with its parent 
with the exception of mere temporary, non-transmit- 
table modifications. If this be true, selection in the 
progeny of a definite homozygote can have no effect. 
That it has no effect has been proved by Johannsen. 
A homozygote consequently is absolutely stable and 
produces offspring which is genetically identical to it. 
Different kinds of homozygotes may be called geno- 
types, because they differ in genetical constitution, and 
we can then say that the world is populated—with 
the exception of heterozygotes—by a large number of 
sharply defined absolutely stable genotypes. Under 
such conditions evolution may well seem impossible; 
fortunately, the behaviour of the heterozygotes shows 
us that it is very well possible. A careful study of 
the descendants of a heterozygote shows us that it 
segregates in the next or later generations in a number 
of individuals, part of which are heterozygous, but part 
of which are homozygous, and that these homozygotes 
belong to different genotypes. It was submitted that 
the real units of the living kingdom are genotypes; 
that such genotypes can, under proper precautions, be 
kept pure for an indefinite time; and that there is no 
certain evidence that they can be changed in any 
other way than by crossing. What then is the reason 
of the apparent variability of a species in the Linnean 
sense? In the first place the fact that a Linnean 
species is a collection of independent stable Jordanian 
species. The author expressed his firm conviction, as 
explained before, that no transmittable variation exists, 
and that all apparent variability is due to an original 
cross. Finally, the author proceeded to the origin of 
species before sexual reproduction took place. 
‘Physical Society, February 13.—Prof. C. H. Lees, 
vice-president, in the chair.—R. LI. Jones : The moving 
coil ballistic galvanometer.—A. Campbell: Vibration 
galvanometers of low effective resistance. The mathe- 
matical theory of the motion of the moving coil of a 
vibration galvanometer is first given (partly following 
Wenner), and simple relations are shown to hold be- 
tween the two resonance frequencies, the free fre- 
quency, and the amplitude time constant. It is also 
shown how all the constants of the equation of motion 
can be deduced from observations of the direct- and 
alternating-current sensitivities, the alternating voltage 
sensitivity and the ‘‘dead”’ resistance. A complete 
table of the observed and deduced constants is given 
for a series of very small coils, the number of turns 
in these varying from one to forty.—Dr. H. J. S. 
Sand: Vacuum-tight lead seals for  leading-in 
wires in vitreous silica and other glasses. The 
author has found that lead which has_ been 
allowed to solidify in contact with glass will, if free 
from oxide, form a vacuum-tight joint with the latter. 
Owing to the very great firmness with which the 
metal adheres, and owing to its great plasticity, these 
joints can stand temperature changes without damage. 
Zoological Society, February 17.—Prof. E. A. 
Minchin, vice-president, in the chair.—Dr. R. T. 
Leiper and Surgeon E. L. Atkinson: The Helminthes 
collected by the British Antarctic Expedition (Terra 
Nova), 1910-13. The collection contained nine forms 
previously recorded from the Antarctic zone, three pre- 
MOM MetAe Vor. 2/02 | 
NATURE 
92 
ac 0 
viously recorded only from the Arctic regions, and one 
other previously recorded elsewhere and now found in 
the Antarctic zone, and fifteen new species and four 
new genera. Of the forms obtained in tropical and 
temperate zones during the voyage, three had been 
recorded previously and five were new species.—C. G. 
Seligmann and S. G. Shattock : The seasonal assump- 
tion of the ‘‘eclipse’’ plumage in the mallard (Anas 
boscas) and the function of the testicle. Though the 
seasonal change of plumage did not correspond with 
the spermatogenic function of the testicle, its connec- 
tion with the production of an internal secretion could 
only be settled by castration followed absolutely with- 
out regeneration; this could be ensured only by re- 
opening the abdomen under an anesthetic and remov- 
ing any reproduced tissue found.—Dr. F. Wood-Jones : 
Some phases in the reproductive history of the female 
mole (T'alpa europea).—H. C. Chadwick : Notes on an 
imperfectly developed specimen of the sea-urchin 
(Echinus esculentus)—C. F. U. Meek: The possible 
connection between spindle-length and cell-volume. In 
Forficula auricularia, Helix pomatia, and man the 
ratio between the lengths of the mitotic spindle in the 
two spermatocyte metaphases seemed to be identical 
or almost identical with the ratio between the radii of 
two spheres, of which the volume of one is equal to 
twice that of the other; and, since the volume of the 
primary spermatocyte cell in the metaphase is presum- 
ably equal to twice that of the secondary spermatocyte, 
connection was suggested between the spindle-length 
and cell-volume at this stage.—F. F. Laidlaw: A 
further contribution to the study of the dragon-fly 
fauna of Borneo. The paper dealt with the Gomphinz 
and Chlorogomphinz, of which a number of new 
species and subspecies was described. 
Royal Anthropological Institute, February 17.—Prof. 
A. Keith, president, in the chair.—S. MHazzledine 
Warren; The experimental investigation of flint frac- 
ture and problems of early man. ‘The paper describes 
experiments conducted for the purpose of investigating 
the chipping properties of flint, when operated upon 
by forces of measured strength. In the case of 
mechanical concussions the chief method employed was 
by the impact of bodies of known weight falling under 
the acceleration of gravity from a measured height. 
Some striking illustrations of the lines of least resist- 
ance in flint were thus obtained. As an instance of 
this, free chipping was obtainea by blows of an energy 
of o-8 foot-pounds, delivered at a velocity of 15 ft. 
a second, in one direction upon a flint. But, at the 
same time, blows of an energy of 22 foot-pounds, 
delivered at a velocity of 18-8 ft. a second, upon the 
opposite side of the same flint, had no effect except to 
continue chipping in the original direction by the 
back-pressure of the support on which the flint was 
placed for experiment. The lines of least resistance 
depend very largely upon the original shape of the 
piece of flint used for the experiment. It is argued 
that these properties must also have their influence in 
the chipping of flints by natural agencies, and may 
well induce a deceptive appearance of purposeful blows 
having been delivered in one direction only. A series 
of experiments showing the effects of differential 
movement under loads of from 14 to 2:0 Ib. are also 
described. The similarity of these mechanical effects 
to the ‘‘eoliths’’ of Kentish type is pointed out. 
Royal Meteorological Society, February 18.—Mr. 
C. J. P. Cave, president, in the chair.—Dr. W. N. 
Shaw: The interpretation of the results of soundings 
with pilot balloons. The author dealt with the calcula- 
tion of the distribution of pressure and temperature 
from the observed horizontal wind velocity at different 
heights and gave examples of the application of this 
method to certain types of atmospheric structure repre-. 
