250 

and imperfect condition they have not hitherto been 
recognised as new. Five species, belonging to four 
new genera, are Therocephalians. Two species, one 
of which belongs to a new genus, are Gorgonopsians, 
and one is a new species of a previously known 
Cynodont genus.—Dr. R. Broom: The organ of 
Jacobson and its relations in the “ Insectivora” 
Tupaia and Gymnura. Gymnura is shown to have 
the same type as is found in Erinaceus, Sorex, and 
Talpa, and most higher Eutherians such as Felis, 
Lemur, Miniopteris, Ovis, Bos, Equus, Procavia. 
Tupaia, on the other hand, has, like the allied Macro- 
scelides, the primitive marsupial type. Peters and 
Haeckel in 1864 and 1866 had suggested separating 
Tupaia and Macroscelides as a suborder of the 
Insectivora, but the condition of the nasal cartilages 
shows that the Menotyphla should form a distinct 
order, not even closely allied to the typical Insectivora. 
Linnean Society, April 15.—Prof. E. B. Poulton, 
president, in the chair.—C. F. M. Swynnerton: Ex- 
periments and observations on the interpretation of 
form and coloraticn in plants and animals. Food- 
preference and other experiments were carried out 
over five years on insectivorous and (later) carnivorous, 
egg-eating herbivorous, and other animals, and 
numerous field-observations made: The work was 
attempted on a large scale and with every precaution, 
experiments on captive insectivorous birds were 
checked (and confirmed), by a series of experiments 
on wild birds, and various objections to a selectionist 
view specially __ tested. Numerous  ‘“‘ deterrent ”’ 
defences were found definitely to exist; also the finest 
gradation from those species of animals and plants 
that are only eaten through hunger, to the few that 
an individual enemy will eat to repletion-point. This 
indicated that the need for distinguishability from 
pleasanter forms (apparent and otherwise) is, and has 
been, widespread, and, with the numerous mistaken 
attacks and unmistaken refusals witnessed, suggested 
a contributory explanation for ‘distinctiveness ’’ and 
diversity generally. Wild fruits were also ‘ graded” 
by their eaters, and preferences shown by insects and 
birds as between even their own flowers; insect-hunt- 
ing bird-parties were watched on a few occasions 
visiting exclusively particular _ temporarily-infested 
species of trees; and the utilisation of appro- 
priate characteristics by animals for intra-specific 
recognition was amply illustrated by field-observation. 
Thus “ distinctiveness”’ (and differentiation) may have 
been very widely selected in relation to ‘‘ friends” too. 
Abundant observation of unmistaken attacks on prey 
and the latter’s reply thereto testified to the great 
importance of the procryptic and actively evasive de- 
fences and to the fact of their appropriate utilisation. 
Moreover, enemies were seen to return expressly ‘to 
stationary prey that they had not been hungry enough 
for on first discovery, and the view that a special 
handicap may prohibit conspicuousness in a group, 
a species, a stage, or a sex was confirmed otherwise 
too. That it is through the existence or development 
of suitable counter-agents (as flight, mauseousness, 
procryptic underside, and special habits) that what- 
ever factors make for conspicuousness have been 
together enabled (in another species, sex, etc.) to 
produce it, was shown; and several such factors were 
indicated, including sexual selection. Animals were 
deterred by resemblances in prey, and a double poten- 
tial basis for mimiery was found definitely to exist; 
also a basis for synaposematism (in flowers synepise- 
matism) in the observed effect of the more numerous 
reminders and simplified recognition that a link in 
appearance or smell would afford. Probable cases of 
mimicry were seen and tested in plants, eggs, and 
birds. More than 800 attacks on butterflies by wild 
NO. 2374, VOL. 95] 
NATURE 


[APRIL 29, 1915 
birds were witnessed. Discriminative action that 
might contribute to selection was actually observed at 
work, interspecifically (as in the preferences shown), 
and intraspecifically (in choice of largest available 
prey, destruction, or artificial entry of inconvenient 
ornithophilous flowers, and individual destruction 
through the inactivity of extra-floral nectaries). 
Mathematical Society, April 22.—Sir J. Larmor, presi- 
dent, and afterwards Prof. Love, vice-president, in the 
chair.—G. H. Hardy: Note on Dirichlet’s divisor 
problem.—Col. R. L. Hippisley: Note on a new form 
of closed lidnkage.—G. B. Mathews: Division of the 
lemniscate into seven equal parts.—-Sir J. Larmor: The 
influence of the oceanic waters on the law of variation 
of latitude. The prolongation of the periodic time of 
the small free orbital motion of the pole over the 
earth’s surface from 304 to 428 days has been recog- 
nised to be due to the centrifugal strain of the earth’s 
rotation changing in step with the changing axis of 
rotation. This regular circular precession is found to 
be strongly disturbed by irregular surface displace- 
ments of terrestrial masses. But among these disturb- 
ances the adaptation of the ocean surface to the chang- 
ing axis ought not to be included, for being syn- 
chronous with the precessional motion it must affect 
its period, and so fundamentally alter it instead of 
merely disturbing it. It is roughly estimated that if 
the earth were elastically unyielding, the effect of the 
existing ocean would be to lengthen the period of 
free precession from 304 to about 332 days. The 
remainder of the actual increase to about 428 days 
would be, as now, ascribed to elastic centrifugal strain 
of the solid earth, and the necessary slight revision of 
current estimates of its yielding is made on this basis. 
The question is broached, What would be the course 
of history of a planet so nearly spherical that the 
incumbent ocean would destroy secular stability for all 
possible axes of rotation? 

DuBLIN. 
Royal Irish Academy, April 12.—Rev. J. P. Mahaffy, 
president, in the chair.—Rey. P. Browne: An integral 
equation proposed by Abel, and other functional equa- 
tions related to it. The paper deals principally with 
rh 
the equation, | G(wj(tx)dt= g(x), where G and g are 
known functions, and f is to be discovered; a and b 
are constants. Abel gave this equation as a general- 
isation of the problem of the isochrone, stating he 
had solved it, but the solution does not appear in his 
published works. A solution is found involving in- 
tegration along an infinite straight line in the plane 
of the complex variable. By extensions of the method, 
the equations, 
ra cr pe 
[Ges 1) f(tx)dt=g(x), | | G(tr) f(tx, ~)dtdr=eix,y), 
J Jolo 
and others, are solved.—A. J. Rahilly: Some geo- 
metrical determinants. The geometrical determinants 
dealt with are of the type exemplified in Frobenius’s 
theorem connecting the mutual powers of two quintets 
of circles. It is shown by a very simple method that 
similar determinantal relations exist between many 
sets of geometrical entities; in fact, a large part of 
the metric geometry of the point, line, circle, plane, 
and sphere may be reduced to such determinant- 
equations. Some new applications are given; in par- 
ticular, Ptolemy’s theorem, which is a special case, 
is given several extensions. 
Royal Dublin Society, March 23.—Prof. W. Brown 
in the chair.—Prof. J. Wilson: Simplified solutions of 
certain Mendelian problems in which factors have 
inseparable effects. The author makes use of two 

