30 6 
SCIENCE. 
gum water, or Brunswick black. For very small objects a 
small circle of the gelatin is turned in the centre of the 
slide, and then allowed to dry. The objects are arranged 
on the spot, and then, by carefully breathing on the slide, 
they are fixed in position. If larger objects are to be fixed 
to the slide a spot of gelatin or gum that the object will 
entirely cover is put on, and after drying, the object is fixed 
in the same way. For larger and heavier objects a circle 
of Brunswick black is turned, and after it has been thor- 
oughly hardened by heat, so that when cool a needle point 
will not mark it easily, the object is arranged on the spot 
and fastened by warming again. 
In whatever way' the object is fastened, the next thing to 
be done is to lay the slide on tne plate and heat it until it 
is perfectly dried and ready to be covered. 
The slide is then centered on the table and a circle of 
shellac, which has been thickened and colored with Chinese 
vermillion, is run around the specimen, at such a distance 
from it that its inner edge is just larger than the cell to be 
used. The cell is then laid on, centered, and pressed hard 
to set it. If the slide is slightly warm and the cement 
thick, it will not run at all, but will hold the cell firmly in 
place, so that the cover can be put on at once. If it is thin 
it must first be allowed to harden somewhat. When read)', 
as it will be in a few moments if properly managed, a ring 
of the same cement is run on the cell and the cover is then 
laid on, pressed down, clipped in position, and the mount 
laid aside to harden. It is well in an hour or so to remove 
the clip and run cement in the joints between cover-glass 
cell and slide, in order to be certain that no air-holes re- 
main. It can then be reclipped, and set aside until the 
cement is perfectly hard. The mount is complete and will 
last a long time if proper care is taken of it. I think for 
security it is well to put on additional rings of cement 
more elastic than the shellac, and to make a final finish for 
the sake of appearance. I, therefore, put on a ring of 
white zinc cement which completely fills up the joints, and 
makes a smooth surface from cover-glass to slide. This 
must harden several days, and the slide is then complete, 
unless additional rings are run on for a finish. 
In making the rings on slides it is not always easy to 
make the edges true, and sometimes the cement spreads 
too far. In such cases I turn them down with the point of 
a knife until they suit. If the cement is taken just at the 
right time this is easily' done, and it improves the appear- 
ance very much.” 
BOTANY. 
The Color of Flowers. — At a recent meeting of the 
Vaudois Society of Natural Science, Prof. Schnetzler read 
an interesting paper on the color of flowers. Hitherto it 
has generally been supposed that the various colors ob- 
served in plants were due to so many different matters — 
each color being a different chemical combination without 
relation to the others. Now, however, Prof. Schnetzler 
shows by experiment that when the color of a flower has 
been isolated by putting it in alcohol, one may, by adding 
an acid or an alkali, obtain all the colors which plants ex- 
hibit. Plants of Paeony, for example, yield, when macer- 
ated in alcohol, a violel-red liquid. If some acid oxalate 
of potassa be added, the liquid becomes pure red ; while 
soda changes it, according to the proportion used, into vio- 
let, blue or green. In the latter case, the green liquid 
appears red by transmitted light, just as a solution of chlor- 
ophyll does. The sepals of Paeony, which are green bor- 
dered with red, become wholly red when placed in a solu- 
tion of acid oxalate (binoxalate) of potassa. These changes 
of color, which may be obtained at will, may quite well be 
produced in the plant by the same causes ; since, in all 
plants, there always exist acid or alkaline matters. Fur- 
ther, it is stated that the transformation from green into red, 
observed in the leaves of many plants in autumn, is due to 
the action of the tannin which they contain, on the chloro- 
phyll. Thus, without desiring to affirm it absolutely, Prof. 
Schnetzler supposes, a priori, that there is in plants only one 
coloring matter — chlorophyll , which, being modified by cer- 
tain agents, furnishes all the lints that flowers and leaves 
exhibit. As for white flowers, it is well known that their 
cells are filled with a colorless fluid, opacity being due to 
air contained in the numerous lacuna? of the petals. On 
placing the latter under the receiver of an air-pump, they 
are seen to lose their opacity and to become transparent as 
the air escapes from them. 
Professor W. W. Bailey, of Brown University, states 
that the herbarium of the late Col. Stephen T. Olney, 
of Providence, R. I., was left by his will to Brown Univer- 
sity, on condition that it be placed in a fire-proof building. 
It is probably known to the readers of “Science” that 
Col. Olney was an invalid and incapacitated for business 
during the last years of his life. At that time the herbarium, 
which had been stored in Butler Exchange, was trans- 
ferred by the trustees to the fire-proof library building of 
Brown University, the only edifice possessed by the college 
which would fulfil the requirements. Professor Bailey 
was requested to examine and arrange the collections, 
which he did in connection with Mr. James L. Bennett. 
He is greatly indebted to this gentleman for valuable 
suggestions and assistance which his natural neatness 
of method and mature experience rendered easily pos- 
sible. He it was who arranged the Carices (which were 
Col. Olney’s specialty), together with the lower Crypto- 
gams, many of which he had himself collected. 
They found this elegant herbarium, one hardly surpassed 
bv any private collection in America, badly injured by in- 
sects. The first work, then, was to poison what could be 
saved. It is not an exaggeration to say that one-third of the 
Phanerogams had suffered. In places a whole genus would 
be riddled by the Anthrenus. It was a sad sight ; for the 
specimens had been prime, were superbly mounted, and 
many of them impossible to replace. Col. Olney was so 
neat in his methods that he disliked to see a blemish on 
any paper ; hence his very sense of order was perhaps a 
means of loss. Every plant had to be thoroughly poisoned, 
Now that the college has come into possession, it will be 
necessary to throw out mutilated specimens and replace 
them by others. Mr. Bennett and Professor Bailey stand 
ready to fill the vacancies from their own herbariums. 
The collection is a fine one in every way. In Rhode 
Island plants it is only equalled by that of Mr. Bennett. 
It is very rich in Southern and Western plants of Hale, 
Chapman, Curtis, Ravenel, Fendler, Parry, Thurber and 
many other well-known collectors. There is a fine set of 
Wright’s Cuban plants, of Robin’s Potamogetons, of Sulli- 
vant’s and Austin’s Mosses, etc., etc. Indeed the owner 
spared no expense (and he was a wealthy man) to build up 
his herbarium. In the genus Carex it must long remain 
unique and classic. There is much raw material and many 
duplicates in Carex. As Colonel Olney’s correspondence 
shows him to have been in debt as regards exchanges, Pro- 
fessor Bailey, who now has charge of the herbarium, would 
be pleased to communicate with such botanists as have not 
received returns. He will then, acting under the direction 
of the college authorities, endeavor to discharge all such 
obligations. Col. Olney bequeathed a fund of $10,000 for 
the increase of his herbarium and library. The latter, con- 
taining 712 volumes also comes to Brown University, to- 
gether with his Chevalier and Smith & Beck’s microscopes 
and much valuable apparatus and material. With another 
$25,000 left by the deceased Colonel, a professorship of 
Natural History has been created. One of the duties of 
the professor is to give lectures on Botany. 
We are under obligations to the Bulletin of the Torrey 
Botanical Club, for occasional botanical notes. This 
Journal has now been published for ten years, and was 
established as a means of communication for botanists. The 
address of the editor is, W. H. Leggett, 54 East 8 1 st 
street, New York City. The rates are one dollar per 
annum, so that its cost will hardly be a bar to its use by 
botanists. We can probably arrange club rates for our 
subscribers, 
