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POPULAR SCIENCE REVIEW. 
fication of mammalia upon similar foundations. The taxological arrangement 
of birds would, he conceives, be somewhat more difficult. The characters 
selected in the mammalian scheme are those of the vertebral column, but as 
the spine of birds is subject to less modification than that of mammals, he 
sums up the total characters of the skeleton in classifying the former, which 
he ranges under four natural orders. 
The Colour of Corals. — Some very interesting observations on this subject 
have been made by M. Lacaze Duthiers, who was sent out by the French 
Government to study the development of the Mediterranean corals. This 
naturalist affirms that the colours of the coral, as we know it, and as it exists 
in the ocean, are in some instances quite different. Thus, he says, Gorgonia 
suhtilis, when taken from the sea, is of a lovely orange red hue, but in most 
writings it is described as being white. The Muricea placomus, which is 
also orange, when in its native element, is represented as being of a blackish 
colour. These differences owe their origin to the circumstance that, in some 
corals, the colouring matter is deposited in the soft tissues, whilst in others it 
exists in the harder parts. In the first case, the cells which compose the 
Sarcosome or walls of the polyps’ bodies, are filled with minute granulations, 
which produce the characteristic tint ; but this matter is of a very delicate 
character, and on exposure to air or fresh water it becomes altered. In the 
second case, the granulations being in the hard calcareous substance, the 
colour is enabled to resist external influences. 
Action of the Cicatricule of the Egg. — The researches of Quatrefages and 
others have shown that the ovum possesses peculiar powers which are quite 
independent of the properties developed after contact with the sperm. Thus 
it is now known that the vitellus undergoes segmentation, whether the ovum 
have been impregnated or not. But recently a new fact has been discovered 
by M. Dareste, who finds that the cicatricule does not share in the general 
process of segmentation^ unless there has been contact of the ovum with the 
^oosperm. 
Progress of Agassi^ s Museum. — Professor Agassiz is certainly accumu- 
lating a monster collection of natural history objects. During the past 
year no less than 73,000 specimens of animals have been added to the 
museum. But this is not all ; of those animals which, from their minute 
size and delicacy of structure, it is impossible to exhibit specimens, enlarged 
and accurate diagrams are made and placed in conspicuous localities. The 
Professor writes : “ Many hundreds of these diagrams have already been 
made by my friend Mr. Bourkhardt, some of which are now on exhibition in 
the museum ; and in a few weeks every available space in our public rooms 
will be occupied by those which have thus far remained in portfolios. This 
wiU greatly add to the interest of our collections, and form a novel feature in 
the museum, which I have no doubt will soon be imitated by others.” The 
Government of Massachusetts has already given the museum authorities a sum 
of 10,000 dols. for an illustrated catalogue, which we believe is now in the press. 
Habits of the Ant. — Few of our readers may be aware that the ant delights 
to capture the aphis, and domesticate it for the sake of the saccharine matter 
which exudes from its abdomen. This fact was long since pointed out by that 
greatest of all observers in natural science, Huber^ who also affirmed that the 
ant went so far as to build habitations for the aphides. The latter statement 
