November 19, 1870.3 THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
401 
STARCH FOR THE MICROSCOPE. 
BY M. C. COOKE, M.A. 
It may be presumed that the time is past when 
the microscope required an apologist. For the use 
of such an assistant in the detection of adulteration, 
or in the discrimination of minute bodies such as 
starch granules, no advocate is needed, because it 
has become a necessity. Even the practised micro - 
scopist, as well as the occasional experimentalist, are 
constantly being made aware by experience, either 
of small errors in observation or greater errors in the 
preservation of microscopic objects. Perhaps as in¬ 
teresting and useful a series as any that could be re¬ 
commended to the majority of the readers of this 
Journal, would be a long and well-authenticated 
series of starches. Unfortunately, however, these 
are best observed when mounted in fluid; and when 
thus prepared, two serious charges of condemnation 
are liable of being pronounced against them. Both 
these failures having occurred in my own cabinet, I 
venture to warn others, in the hope of preserving 
them from similar disappointment. The first charge 
may be preferred against all fluid mountings, that if 
left alone, even when flat, for a few years, the gold 
size or other substance of which the ring, or shallow 
cell is composed, flows in and discolours the starch, 
or there is a tendency to leakage, minute it may be, 
but enough to become annoying. The second charge 
is a far more important one, and that to which I de¬ 
sire more particularly, and specially, to direct atten¬ 
tion. All starches mounted in fluid of any kind that 
I have seen employed, exhibit in the course of time 
a great tendency to change, so much so that in many 
instances they become of little or no value as tests 
in the comparison of closely allied forms. Some 
have become utterly valueless in four or five years. 
The only safeguard that I am prepared to recom¬ 
mend is that which I am now adopting, of mounting 
with every specimen that is put up “ in fluid” a du¬ 
plicate mounted “ dry.” Both can be accommodated 
on the same slide, which for many reasons is prefer¬ 
able ; still, with all drawbacks, starch mounted dry 
is not liable to change, and to become so utterly 
valueless, as when mounted in fluid. The more de¬ 
licate the starch, the more fatal the change. By com¬ 
paring freshly mounted specimens with old ones, this 
change is painfully manifest. 
Besides mounting starches dry, which only require 
a ling of old gold-size the size of the cover, and no 
deeper cell, they may be put up in balsam, or in bal¬ 
sam and chloroform, or in gum dammar dissolved in 
benzine. Pale copal varnish is not at all a bad sub¬ 
stitute for balsam in mounting, but not so good as 
the gum dammar dissolved in benzine. Select a nice 
clean piece of dammar, break it up and place in a 
wide-mouthed bottle, cover well -with benzine, let it 
stand till dissolved, shaking occasionally, and if too 
thick, add more benzine, until when well mixed it 
drops freely. If too thin, by leaving the bottle open 
the benzine will soon evaporate sufficiently to obtain 
the desired density. In the course of time this me¬ 
dium is sure to become too thick for use, but the ad¬ 
dition of benzine, stirring all together, and then 
allowing it to stand until perfectly clear, will soon 
remedy this defect. If this substance had but a fair 
trial, I think, as no heat is required in mounting, 
that it would almost wholly supersede balsam. In 
fact, I have never used a drop of balsam for any- 
Third Series, No. 21. 
thing since I became acquainted with “ dammar in 
benzine.” 
Tliis communication would hardly be complete 
without a reference to the methods which may be, 
or are, employed in mounting starches for the micro¬ 
scope. Besides the dry method, and mounting in 
resinous media, the following have been recom¬ 
mended :— 
Camphor water is one of the common media that 
are employed for starches and other vegetable or¬ 
ganisms. A lump of camphor is placed in a bottle 
of distilled water, so that as much of it as possible 
may be dissolved. One grain each of baysalt and 
alum are added for each ounce of water, or a drop or 
two of creasote is shaken up with each ounce of 
water, which is afterwards filtered. 
Glycerine is also used, especially when diluted 
with two parts of the above camphor water. It is 
worthy of remark that when glycerine is employed as 
a medium, gum dammar in benzine is excellent for 
securing the covers, because the exudation of any 
small quantity of the glycerine around the edges of 
the cover is no obstacle to the adherent properties of 
the dissolved dammar. In fact, a drop of glycerine 
may be let fall upon the centre of a slide, starch may 
be dusted over it, a thin cover, round or square, laid 
on and pressed flat, and held by a clip ; all the gly¬ 
cerine winch is pressed out beyond the edges of the 
cover may then be wiped away, and gum dammar in 
benzine run round the edges of the cover. In twenty- 
four hours the dammar is dry enough to remove the 
clip, and in a few days the slide may either be covered 
with paper, or the dammar may be trimmed off a 
little, and a coat of black varnish painted over it. 
If not used for starches, this mode of mounting is 
good for many objects, and glycerine is much more 
manageable than by any other method, owing to 
the greater affinity between the glycerine and ben¬ 
zine. 
Glycerine and gum, mixed in the following pro¬ 
portions may be used : one ounce each of gum arabic, 
glycerine and distilled water, with one and a half 
grains of arsenious acid. The latter is dissolved in 
the cold water, then the gum, and lastly the glyce¬ 
rine are added and mixed. 
Castor oil is a veiy troublesome fluid to use, but it 
has been employed for starch, though with no corre¬ 
sponding advantage. 
Alcoholic fluids are always objectionable, on ac¬ 
count of their solvent power upon most of the sub¬ 
stances used for securing the covers. 
Of all the media employed for starches, where 
employed at all, none are equal in my estimation, 
not even balsam, to gum dammar dissolved in ben¬ 
zine. When the polariscope is to be used, this plan 
should be adopted, and certainly no one would sup¬ 
pose an examination of starch complete without the 
aid of polarized light. 
In his recent lectures on “ Microscopical Manipu¬ 
lation,” Mr. W. T. Suffolk has expressed similar 
flews on this subject, “A series of starches from 
various plants should be mounted and kept for com¬ 
parison. Two slides of each should be prepared, 
one dry, the other in balsam for examination with 
the polariscope. When starch is mounted in balsam, 
care should be taken to employ as little heat as pos¬ 
sible. Starch granules are not well preserved in 
fluids.” The use of “ dammar ” instead of “ balsam 
obviates the employment of heat at all, and con¬ 
sequently is preferable. In conclusion, I would 
