May 25, 1899] 
NATURE 
93 
transferring vigorous young mycelia to thin shavings of horn has 
observed the infection of the latter. 
It thus becomes evident that the spores of Oxygena pass 
through the body of an animal in nature, and, as might be ex- 
pected from this, extract of the animal’s dung also affords a 
suitable food medium for the fungus. Probably the cattle lick 
the Ozygena spores from their own or each other’s hides, hoofs, 
horns, &c., and this may explain why the fungus is so rarely 
observed on the living animal: it is recorded from such in at 
least one case however. 
Very little is known as to the constitution of horn, and some 
experiments have been made to try to answer the question— 
what changes the fungus brings about. The research has bear- 
ings on the question of the decomposition of hair, horn, feathers, 
hoofs, &c., used as manure in agriculture; and may be not 
without significance in throwing light on the destruction of 
cuticle, hair, &c., by parasitic fungi. 
“The Thermal Expansion of Pure Nickel and Cobalt.”’ 
A. E. Tutton, B.Sc. 
F.R.S. 
The author has carried outa series of re-determinations of the 
coefficients of thermal expansion of these two metals with the aid 
of the interference dilatometer described in a former communica- 
tion to the Society (PAz7. Trans., A, vol. exci. p. 313; Roy. Soc. 
Proc., Vol. \xiii. p. 208). Since the determinations made by Fizeau 
in the year 1869, a large amount of additional knowledge has 
been accumulated with reference to nickel and cobalt, including 
the discovery of the liquid nickel carbonyl, which places pro- 
cesses of purification in the hands of the chemist of a character 
so superior to the older methods, as to render it highly desirable 
that re-determinations of the physical constants of these inter- 
esting elements should be carried out with specimens of the 
metals thus purified. By the kindness of Prof. Tilden, who 
has prepared such specimens with infinite care for the purposes 
of the investigation of other physical and chemical characters, 
the author has been enabled to carry out determinations of the 
thermal expansion with rectangular blocks varying in thickness 
from 8 to13 mm. The blocks were furnished with parallel and 
truly plane surfaces by the makers of the dilatometer, Messrs. 
Troughton and Simms. The range of temperature of the 
observations was from 6° to 121°. 
The results of the determinations of the coefficients of linear 
expansion a are as follows :— 
By 
Communicated by Prof. Tilden, D.Sc., 
ek a + 26t. 
For nickel ... a = 0°000 012 48 + 0'000 000 o14 8-4. 
For cobalt ... a = 0'000 O12 08 + 0°000 000 o12 S-¢. 
The coefficients of linear expansion @ of pure nickel and 
cobalt thus exhibit a slight but real difference, the coefficient of 
nickel being distinctly greater than that of cobalt. This is true 
with respect to both the constant a, the coefficient for 0°, and 
the increment per degree, 24, of the general expression for the 
coefficient at any temperature 7, a = a + 26¢. The difference is 
consequently one which augments with the temperature ; at o° 
it amounts to 3°2 per cent., while at 120°, the upper limit of the 
temperatures of the observations, it attains 4°5 per cent. Similar 
rules apply naturally to the cubical coefficients. The metal 
possessing the slightly lower atomic weight, nickel, is thus 
found to expand toa greater extent than the metal, cobalt, which 
is endowed with the higher atomic weight. 
“‘Tmpact with a Liquid Surface, studied by the aid of Instan- 
taneous Photography. Paper II.” By A. M. Worthington, 
M.A., F.R.S., and R. S. Cole, M.A. 
This paper is a continuation of a paper under a similar title, 
published in the Phzlosophical Transactions, vol. clxxxix., 1897. 
It was there shown that, between the splash of a rough and of 
a polished sphere falling the same distance into water, there is 
a remarkable difference from the first moment of contact. The 
causes of this difference are now investigated. 
The configuration of the water surface below the general 
level, when a rough sphere enters, is first studied by instan- 
taneous photography, and the origin is traced of the bubble 
that follows in the wake of the sphere and of the emergent jet 
which follows its disappearance. The depression or crater 
formed round the entering sphere is surprisingly deep. This 
cavity segments, the lower part following as a bubble in the 
wake of the sphere, while the upper part fills up by the influx of 
surrounding water, which gathers velocity as it converges 
towards the axis of the disturbance, and so produces the upward 
spirt of the jet. 
NO. 1543, VOL. 60] 
oi dl 
The actual displacement of the liquid has been studied by 
letting the sphere descend between two vertical slowly ascend- 
ing streams of minute bubbles liberated by electrolysis from two 
pointed electrodes. 
The splash of a smooth sphere is traced by gradual transition 
into that of a rough one as the height of fall is increased. But 
the course of the disturbance is largely dependent on minute 
differences in the condition of the surface, and even on its tem- 
perature. It was further found that dropping a smooth sphere 
through a flame, under certain conditions, invariably alters en- 
tirely the course of the splash. This action of the flame is 
proved to be no action of electrical discharge, and reasons are 
given for attributing it to the burning off of fine dust which has 
collected on the surface during the fall. 
The influence of dust was proved by dusting one side only of 
a polished sphere, a proceeding which always results in com- 
pletely changing the character of the splash on the dusted side. 
A satisfactory general explanation of all the phenomera is 
found in the view that with a smooth sphere, cohesion is 
operative in guiding the advancing edge of the liquid sheath 
which rises over and closely envelops the sphere. If the surface 
is not rigid (e.g. is dusty), or is rough, then the momentum of 
the sheath carries it, once for all, away from the surface of the 
sphere, and the subsequent motion is quite different. The per- 
sistence of the remarkable radial ribs or flutings observable im 
the film that ensheaths a smooth entering sphere is com- 
pletely explained by the assumption of a viscous drag spreading 
from the surface of the sphere outwards, and these flutings are 
always absent from any part of the sheath that has left the 
sphere. Their presence is thus an indication that there is no 
finite slip at the solid surface. 
Experiments 2 vacuo show that the influence of the air is 
quite secondary. The similarity of the splash in a liquid with 
that due to the impact ofa steel projectile on an armour-plate 
is referred to as requiring further investigation. 
‘*The External Features in the Development of Lepedosiven 
paradoxa, Fitz.” By J. Graham Kerr. Communicated by A. 
Sedgwick, F.R.S. 
The eggs, averaging between 6'5 and 7 mm. in diameter, are 
deposited in a burrow at the bottom of the swamp. They are 
of a pale salmon colour without a trace of dark pigment. Seg- 
mentation closely resembles that of 47za. Gastrulation begins 
with the appearance of a row of depressions, or a continuous 
groove, running round about one-third of the length of the 
boundary between large and small cells. As this deepens to 
form the archenteron it shortens up, and the ultimately formed 
crescentic blastopore is only about a quarter of the length of the 
original groove. The medullary folds are low and inconspicuous, 
and meet behind the blastopore, which later becomes the anus. 
The over-arching of the medullary folds towards one another 
takes place to a certain extent, but the canal so covered in soon 
disappears, and the central canal of the nervous system is a 
secondary excavation. There is no trace externally of a frofo- 
stomal seam running along the floor of the medullary groove. 
A somewhat tadpole-like larva hatches out, which assumes a 
remarkably amphibian appearance. This develops on each side 
four large pinnate external or somatic gills, upon branchial 
arches I, II, III, and IV. A large cement organ is also 
present, which during its early stages has the crescentic or 
U-shape so frequent in the embryos of Anura. Both cement 
organ and somatic gills are purely larval structures. During the 
atrophy of the latter they come by differential growth to be 
situated just over the fore limb, giving a similar condition to 
that well known in Protofterus of a larger growth. 
The paper concludes with remarks of a general character upon, 
the phenomena described. 
Linnean Society, April 20.—Dr. A. Giinther, F.R.S., 
President, in the chair.—Mr, George Murray, F.R.S., exhibited 
several slides of new Peridinéaceae, and gave some account of 
the method of collection by pumping, which had been found 
most efficacious with these organisms.—Mr. J. B. Carruthers 
communicated some observations on the localised nature of the 
parent characters in hybrid fruits of Zeobroma cacao, on which 
some Criticism was offered by the Rev. G. Henslow.—Mr. H. H, 
W. Pearson read a paper on the botany of the Ceylon 
‘*patanas,’’ large savannahs in the forests at the same sub- 
tropical levels, and with the same climate, though not peculiar 
to Ceylon. These ‘‘patanas”’ appear to maintain their limits 
for long periods ; but whether they thus exist on account of the 
