THE MEDITERRANEAN NATURALIST 
19 
reduction which not only systematises simply and 
• clearly the knowledge already acquired, but will 
greatly facilitate the progress of future investi- 
gations. 
Some of these changes take effect in the volume 
before us, which embraces the Cephalopoda and 
the Gasteropoda, and the rest will, no doubt, be 
introduced in subsequent volumes. 
Of the technical descriptions which make up 
the great bulk of the volume, we need only say 
that they are as full, as precise, and as vivid as 
could be wished, and include no useless or super- 
fluous details. 
The Oxycephalids by Carl Bovallins. 
This exhaustive and elaborate memoir, written 
by the professor of Natural History in the Uni- 
versity of Upsala constitutes an important addi- 
tion to the literature on the Amphipoda. 
From the introduction, we learn that the author 
had a two-fold object in view in thus publishing 
the results of his researches, the first in order that 
he might have an opportunity of stating his rea- 
sons for the systematic arrangment of the genera 
and species of the Amphipoda that he has adopted, 
and secondly in order that he might be able to 
commucate some fresh results that he had recen- 
tly obtained. 
The memoir is divided into four parts. 
I. Historical notes on the Oxycephalids. 
II. The systematical position of the Oxycephalids, 
III. Morphological notes on the Oxycephalids. 
IV. The Oxycephalidean genera and species. 
The value of the work is still further enhanced 
by the profuse manner in which it is illustrated, 
there being 87 illustrations in the text, and 7 
appended plates. 
Preservation of the colours of plants,. 
BY G. D. I)RUCE, M.A., F.L.S. ( 1 ) 
One great complaint about dry plants is that 
the colour goes or becomes altered, but a great 
deal may be effected by careful drying. 
(1) From a paper “ The History of Botany — 1 
Herbaria ' read before the Chemists Assistants' j 
Association London . 
My friend, Dr. Sehonland, told me of a plan 
they had in the Beilin herbarium of dipping the 
specimen in three parts of sulphurous acid and 
one of methylated spirit. 
The flowers are immersed until bleached, or in 
the case of white ones, from a few seconds to 
seven minutes, according to the texture of the 
flower; they are taken out, and the superfluous 
moisture allowed to be absorbed by a piece of 
bibulous paper, and then dried in the ordinary 
way. Gradually the colour comes back and is then 
permanent. 
The rationale of the process appears to be this. 
The destruction or alteration of the plants colour 
in drying is probably owing to a ferment. We 
know that hay allowed to ferment or heat becomes 
spoiled. 
So with herbarium specimens, overheating or 
allowing them to remain in damp papers is abso- 
lutely destructive to colour. Some colours appear 
to be especially fugitive or sensitive. Blues become 
brown, whites become brown or black, pinks 
change to brown, and yellow sometimes changes to 
green. Now, I take it, the sulphurous acid not 
only deoxidizes the colour, but, combined with 
methylated spirit, destroys the ferment. On 
exposure to air, or in process of time, the plant 
again becomes oxidized and the colour reappears. 
That the spirit may be useful in hardening the 
cell w r all is also probable. There is some difficulty 
with flaccid flowers, for when dipped in the solu- 
tion they become so pulpy as to render it very 
difficult to lay them out properly. Such specimens 
may be first put in parchment paper, and pressed 
in it. 
It answers admirably for our Oampanulacoe, 
Orchidacaoe, and also for the parasitic Cusciita or 
semi-parasitic Lathrea, Bartsiana, and Orobanche. 
My experience is that pink colours are generally 
darkened by it. I am told it answers well for the 
Cow-wheats and Asperula. My experience with 
the former is not as yet satisfactory. Care must 
be taken to use fresh sulphurous acid free from 
sulphuric. I have found that slight traces of the 
latter are sufficient to change delicate blues to 
pink, and thus to give false impressions. 
