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POPULAR SCIENCE REVIEW. 
anatomy and physiology of Dicotyledons ; and the Gegner (4,000 francs) 
to good works on fossil botany, approved by M. Brougniart. 
The Colouring Matters of Plants. — A most important paper on this subject 
is that by Herr N. Pringsheim, in the “ Journal of Botany ” for April (repro- 
duced from the “ Monatsbericht ” of the Academy of Berlin). He says, towards 
the conclusion of his valuable paper : “It must now appear evident why I 
could not agree with Fremy, Filhol, or Kraus in their descriptions of the 
green and yellow chromules, and still less with Sorby respecting the several 
chromules which he alleges to have obtained from various plants, and which 
he regards as distinct and undecomposed substances pre-existing in the 
plants, and capable of definite analysis. It is certain that many of these 
chromules must have been deprived of their original spectrum characteristics 
by the treatment to which they were subjected. In the determination of 
the spectra, moreover, the influence of the solvents, that of concentration, 
and of the thickness of layers, seems to have been equally disregarded. It 
is clear that a single spectrum can give us no adequate information as to the 
absorption phenomena of any chromule, unless we are acquainted before- 
hand with its phases of absorption, and know to which phase of the bands 
it corresponds. Sorby has nowhere stated, with reference to his yellow 
chromules, to which he ascribes two separate bands in the blue, to what 
extent the various positions of the bands are influenced by the solvents, nor 
how they depend on the thickness of the layers ; nor does he state, that with 
an increase of the chromule additional bands do not appear. I doubt not 
that the whole, perhaps, of his yellow chromules — one only excepted — 
would suddenly reveal also the chlorophyll bands of the first half, if my 
method were applied.” 
The Membrana Nuclei in the Seeds of Cycads. — A very capital paper was 
read on this subject before the Linnsean Society, by Professor Thiselton 
Dyer, which is thus abstracted in the “Journal of Botany ” (April, 1875) : — 
“ Heinzel had described this as a cellular structure, the cells of which had 
thick walls penetrated by ramifying tubes. There was reason, however, for 
believing that the membrane only represented the wall of a single cell, and 
was in fact probably the greatly enlarged primary embryo-sac. What 
Heinzel had taken for cells seemed really to be solid. They were arranged 
all over the membrane, after the fashion of what carpet manufacturers call a 
i moss pattern.’ They were possibly the debris of the thickened walls of the 
cells of the nucleus which had been destroyed by the enlargement of the 
primary embryo-sac.” 
The Observation of Plants. — A conference consisting of delegates from the 
Agricultural, Botanic, Boval Dublin, Horticultural, and Meteorological 
Societies, has, at the request of the last-mentioned, drawn up some “ in- 
structions ” for the observation of the appearance of certain plants, insects, 
and birds. In the preparation of these instructions the conference was greatly 
assisted by the Rev. T. A. Preston, of Marlborough College, who has worked 
for many years laboriously at such records. A list of seventy-one of the most 
widely-distributed and commonest plants is given, and those who cannot 
undertake to observe so many are requested to pay attention to fourteen of 
them printed in capitals. This is followed by some very necessary in- 
structions, and a table of the average dates for ten years, as observed at 
