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POPULAR SCIENCE REVIEW. 
however, this character, when once determined, is perfectly fixed to each 
species, it is not linked with any other, and consequently two species very 
analogous may present fruits, in the one, annual, and in the other, 
biennial. 
Colouring Matter of Flowers . — •“ The Natural History Review ” gives 
the observations of M. Hildebrand upon this subject, the conclusions of 
which are, that the colours of flowers are in constant connection with the 
contents of the cells, and never with the cell-wall. Blue, violet, or rose- 
colour, and (if there be no yellow) deep red, are due to a cell-fluid of cor- 
responding colour ; while yellow, orange, and green, are usually associated 
with solid granular or vesicular substances in the cells. Brown or grey, 
and, in many cases, bright red and orange, apparently uniform to the 
naked eye, are found to be compounded of other colours ; as yellow, 
green, or orange, with violet or green and red ; bright red and orange in 
like manner of blue-red with yellow or orange. Black, except in the 
bean, is due to a very deeply coloured cell-fluid. All the cells of an organ 
are very rarely uniformly coloured, and the colour usually resides in one 
or in a few of the outer layers of cells, while the coloured cells are but 
exceptionally covered by a layer of uncoloured ones. Combinations of 
colour are occasioned bv diversely coloured matters in the same or in 
adjacent cells. 
New Botanical Journal . — In order to fill up an acknowledged want, a 
scientific Botanical Magazine has just been issued by Mr. Hardwicke. It 
is called the “ Journal of Botany, British and Foreign,” and is under the 
able editorship of Dr. Seeman. The second number is published. 
R. LETIIEBY’S annual report on the sanitary condition of the 
City of London was issued a short time ago, from which it appears 
that although during rainy weather there is no upward flow of sea water, 
in the summer time a great quantity finds its way up the river, and 
necessarily it will bring with it the sewage which the Board of Works 
have been taking so much trouble to remove out of harm’s way. It will 
probably be brought back beyond the Houses of Parliament, and will be 
all the more unpleasant for being mixed with sea water ; to add to the 
difficulty, there has not as yet been proposed any satisfactory remedy for 
the evil, and in fact the question what to do with the sewage is in very 
much the same state as when it was first brought before the attention of 
the public ; everyone agreeing that something must be done to remedy 
the evil, but no one being able to satisfactorily answer the question — what 
is to be done \ The Chinese manage these matters much better than we 
do in England, and instead of throwing that which is in reality an immense 
fortune into the sea, carefully preserve it. The Chinese greengrocer 
every morning when he leaves the vegetables carries away with him this 
objectionable matter, which is then applied to the fertilization of the soil ; 
this no doubt accounts for its fruitfulness in that country. Of course the 
difficulties of employing a process of this nature in a town like London 
CHEMISTRY. 
