508 
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NATURE 
[March 29, 1883 
as those of barndoor fowls to ourselves. I have stayed at a 
farm at Cape Point, where a pair of the birds were nesting 
within fifty yards of the house, in a small paddock, and have 
seen the hen on the nest. 
An interesting subject of inquiry, however, seems to me to be 
still open in the matter. It is, How far do the habits of nidifi- 
cation of the ostrich vary in the different climates through which 
it ranges? The nest of the ostrich is commonly described as a 
heap of sand, and so no doubt it is in warm desert regions ; but 
the nest which I saw at the Cape was carefully built of grass and 
other warm materials, so as to aid in retaining heat. The birds 
kept the nest almost constantly covered between them. 
In warmer regions, however, the hen appears often to leave 
the nest in the daytime, and it is just possible that where the 
temperature is very high the hen may not incubate at all, and 
the cock alone may do so at night. I merely wish to point out 
that it should not be assumed that the habits of the ostrich as to 
incubation are necessarily the same in the various climates of 
Africa with those to be observed in the Cape region. 
T have noticed that at the Zoological Gardens the ostriches at 
the breeding season are supplied every year with a cartload of 
silver sand as the traditional nest. It would not be amiss to try 
them with some more substantial materials as an experiment, 
and prove whether in our climate they would not build a warm 
nest as at the Cape. 
That birds’ eggs can be hatched like those of turtles in mere 
sand is undoubtedly a fact. The Megapodius inhabiting Cape 
York, Australia, makes, as is well known, a huge mound of 
vegetable matter, which by decomposition supplies the necessary 
warmth to hatch the egss ; but at the Philippine Islands another 
Megapodius buries its eggs in the perfectly clean calcareous sand 
near the seashore. 
The habits of the emu in nesting have been carefully watched 
at Blenhein. The head keeper told me not long ago that the 
cock alone incubates. The hens lay their eggs anywhere about 
in the grass, the cock builds a nest, and rolls the eggs to it, the 
hen sometimes endeavouring to prevent him and to break them. 
I believe an account of observations on the habits of the emu 
at Blenheim were published by Mr. Frank Buckland. 
H. N. MoseELry 
Bonchurch Hotel, Isle of Wight, March 26 
Holothurians 
My experience of about three months in Bermuda and Jamaica 
fully bears out Mr. Guppy and Mr. Kent’s view that the Holo- 
thurians do not feed on living coral. They were moderately 
common in both localities close to the shore, where corals are 
comparatively scarce, and are mainly of the massive kinds, such 
as the Astrzeas, against which the tentacles of a Holothurian 
would be useless. There were a few branching Oculinas here 
and there, but not enough to support the Holothurians. But 
further, some of the latter bury their bodies in the mud or sand, 
leaving only the tentacles exposed ; and I have watched these 
thrusting their tentacles into their stomachs right up to the base 
in the comical way described by Mr. Kent. It is quite clear that 
these were not feeding on living coral. I did not, however, see 
them actually taking up sand and shell and thrusting it down, as 
Mr. Kent did; in fact I was puzzled as to what they were feeding 
on. From the way the tentacles were set, standing nearly erect, 
I fancied they were catching swimming creatures, as other 
tentacled animals do. This idea is supported, though not 
proved, by a fine specimen from the Zoological Station at 
Naples, which has a half-swallowed fish protruding from its 
mouth. The specimen is in the Bristol Museum. It proves at 
all events that they do not reject this kind of food. Possibly in 
default of it they may fall back upon sand and shell, and the 
minute organisms contained in these. Some of my expe- 
riences with these creatures were interesting. At Bermuda 
two large kinds u-ed to lie quite exposed in shallow water. 
I might have guessed from this that they would probably be 
protected in some way. I used to wade along shore carrying a 
fishing-basket and a landing-net, and one day, as my basket was 
full, I put a couple into the landing-net to carry home. As 
their skins were quite hard, I thought they would travel well so. 
After handling them, I found my hands smarted a little, and 
the irritation lasted till bedtime. I found that little bits of their 
skin had got under mine, and this caused the irritation. As I 
was going home, I found my Holothurians were literally melting 
away ; long streamers of a colourless gelatinous substance were 
hanging down between the meshes. Of course I threw the 
nasty things away, and had a dreadful job to get the net clean. 
I attributed my misfortune to the sun, so another day I packed 
a couple up comfortably at the bottom of my basket, which is. 
very elosely made. After an hour or two I was horrified to find 
long streamers hanging down from the basket of the same 
horrible substance. They had literally gone to pieces again, and 
spoilt everything inthe basket. Shortly after, I left for Jamaica, 
and there [ took out a wide-mouthed bottle and brought one 
home in triumph. Being engaged that evening, I left the Holo- 
thurian in the bottle all night. Next morning the creature was 
all there, but he had cleared out the whole of his inside; his 
intestinal canaland the beautiful tree-like organ were perfect. 
The latter was still alive and was waving about in the water in 
the prettiest way, and looking remarkably like branchiz. Some 
accessory organs along the intestinal canal were exhibiting 
rhythmical pulsations. Altogether it was a most interesting 
sight. But my poor H>lothurian was only a tube. I did not 
know at the time that he could grow a complete new inside. 
Clifton College J. G. GRENFELL 
The British Circumpolar Expedition 
SUPPLEMENTARY to the very interesting notice in NATURE 
(p. 484) of the above expedition, permit me to give a brief 
extract from a letter recently received from Capt. Dawson, as 
follows :—‘‘I have heard of a large cavern about a day from 
this (Fort Rae), which I shall try and explore, There are some 
eyeless fish that live there, that I hope may turn out to be a new 
species.” I do tru-t Capt. Dawson may ve able to carry oat his 
intention, but he must be heavily weighted with work, in which 
he appears to take a deep interest. I had long ago been told of 
this cave and its fish, but had no time to visit it, never having 
been within one or two hundred miles of the place. 
March 24 J. RAE 
Meteor 
Mr. MASHEDER’S account in your last number of NATURE 
(p. 483) of the meteor seen by him at Ashby-de-la-Zouch on 
March 17, corresponds in some particulars with the inclosed note 
of one seen by myself on the same evening at Malvern. I am 
therefore inclined to send it you. 
The discrepancies are in the time, which Mr. Masheder states 
to have been 7.5, while here the metecr passed at 6.56 p.m. ; 
also in his description of ‘‘ pieces dropping,” I noticed no such 
appearance, but simply the not unusual one of rapidly recurring 
scintillations in the train. 
Great Malvern, March 17, 6.56 p.m. 
This evening a bright flame-coloured meteor with a short 
scintillating train, nucleus the brightness of Jupiter, passed. 
rapidly across the sky. When first seen it was beneath the 
moon, then shining brightly, and was apparently about the alti- 
tude of Betelzeux, at that time nearly Io past the meridian. It 
disappeared behind the hills almost due west, but so quickly that 
it was difficult to determine its course with any exactitude. 
Lambert House, Great Malvern, March 25 E. BROWN 
Mimicry 
Sucu remarkable instances of mimicry as that described by 
the Duke of Argyll in NATURE, vol. xxvii. p. 125, as occurring 
in a moth, make heavy demands upon the faith of the non- 
scientific reasoner, since it seems to him impossible that organic 
Nature in her ‘‘blind groping in the dark” could, under any 
imaginable combination of circumstances, have succeeded in 
taking the successive steps requisite to bring her to such a state 
of perfect adaptation to condition. But the proverbially keen 
sight of birds, as at present organised, is apt to lead to erroneous 
» inferences with regard to the evolution of protective mimicry in 
their insect prey, seeing that the high develop:nent of this faculty 
now attained by them renders nugatory any disguise that is not 
almost perfect. The theory of natural selection, however, 
requires the gradual perfecting of this, no less than of other 
structural and physiological acquirements ; and there is no 
reason for supposing that the Ornithoscelidan ancestors of the 
feathered tribes possessed exceptional visual powers, but rather 
that the reverse was the case; so that it may be concluded that 
improvement in vision and in rapidity of flight proceeded part 
passu, This being granted, the initiatory steps of mimicry in 
