1876 .] 
Microscopy . 139 
the same in height, into which fits loosely a weighted plug. To the lower end 
of this plug is cemented a piece of chamois leather. Another piece of leather 
is stretched upon a flat piece of wood or plate-glass, to form a pad, which 
completes the apparatus. In using, the tube is placed on the pad, and the 
thin glass, after breathing on, dropped in; the plug is then inserted, and, 
holding the tube well down on the pad, any amount of rubbing can be used 
with perfed safety, the weight of the plug giving sufficient pressure. 
The subjed of double staining of wood and other vegetable tissues has been 
experimented upon by Dr. George D. Beatty, of Baltimore: the results will be 
found useful to those interested in preparing tinted sections. The author has 
discovered that benzole instantly fixes any aniline colour in vegetable tissues, 
and also renders them as transparent as oil of cloves. The following are the 
processes adopted : — A. sedion of wood or other vegetable substance, being 
prepared for dyeing, is put for five or ten minutes in an alcoholic solution of 
roseine pure (magenta), one-eighth or one-quarter grain to the ounce. From 
this it is removed to a solution of “ Nicholson’s Soluble Blue Pure,” one-half 
grain to the ounce of alcohol acidulated with one drop of nitric acid. In this 
it should be kept for thirty or ninety seconds, rarely longer. It should be fre- 
quently removed with forceps during this period, and held to the light for 
examination, so that the moment for final removal and putting into benzole be 
not missed. After a little pradice the eye will accurately determine the time 
for removal. Before placing the objed in benzole it is well to hold it in the 
forceps for a few seconds, letting the end touch some clean surface, that the 
dye may drip off, and the objed become partially dry. By doing this fewer 
particles of insoluble dye rise to the surface of the benzole in which the 
brushing is done to remove foreign matter. The objed should then be put into 
clean benzole. In this it may be examined under the glass. If it is found 
that it has been kept in the blue too short a time it should be thoroughly dried, 
and after dipping in alcohol be returned to the dye. If a sedion of leaf or 
other soft tissue be under treatment it should be put in turpentine or oil of 
juniper » as they do not cause so much contradion as benzole. When hema- 
toxylin is used instead of magenta, it is followed by the blue as just described. 
As neither of these dyes come out in alcohol or oil of cloves, the sedion may 
be kept in the former for a short time before placing in the latter. The 
hematoxylin dye preferred by Dr. Beatty is prepared by triturating in a mor- 
tar for about ten minutes two drachms of ground campeachy wood with one 
ounce of absolute alcohol, setting it aside for twelve hours, well covered, 
triturating again and filtering. Ten drops of this are added to forty drops of 
a solution of alum ; twenty grains to the ounce of water. After an hour the 
solution is filtered. Into this the sedion, previously soaked in alum water, is 
placed for two or three hours, or until dyed of a moderately dark shade. 
When dyed of the depth of shade desired, which is determined by dipping it 
in alum water, the sedion is successively washed for a few minutes each, in 
alum water, pure water, and 50 per cent alcohol. Finally it is put in absolute 
alcohol until transferred to the blue. Carmine and aniline blue produce 
marked stainings, but they are rather glaring to the eye under the microscope. 
An ammoniacal solution of carmine is used, double the strength of Beale’s, 
substituting water for a glycerine. In this a sedion is kept for several hours. 
On removal it should be dipped in water, and then put for a few minutes in 
alcohol acidulated with 2 per cent of nitric acid ; then in pure alcohol ; then 
in the half-grain blue solution before spoken of, from which it should be re- 
moved to alcohol ; then to oil of cloves. Much colour will be lost in the acid 
alcohol. The acid is to neutralise the ammonia which is inimical to aniline 
blue. Magenta or haematoxylin may be used with green instead of blue ani- 
line. Iodine green is to be preferred, one grain to the ounce of alcohol. 
Double stainings of leaves in which red is first used have the spiral vessels 
stained this colour, other parts being purple or blue. Radial and tangential 
sedions of wood have the longitudinal woody fibres red, and other parts purple 
or blue. This seledion of colour is supposed by Dr. Beatty to be due to the 
fad that spiral vessels and woody fibres take up more red than other parts, and 
are slower in parting with it. The blue, therefore, seems first to overcome the 
