RECORD OF MEDICAL SCIENCE.
ANATOMY AND PHYSIOLOGY.
An Account of a Chemico-Gelatinous Injection, with the method of
employing it in Anatomical Preparations. By Henry Goadby, Esq.,
F. L. S., late dissector of Minute Anatomy, to the Royal College of
Surgeons, of England.
At the latter part of the year 1841, I was desirous of making a series
of minutely-injected preparations to illustrate the peculiar arrangement
of the capillary vessels in the different tissues of the human subject.
My experience of the materials usually employed for this purpose—i. e.,
common size, or parchment size, colored with vermillion, left but one
impression on my mind—viz., that the particles of the finest vermillion
are too coarse to pass through the capillary system. Occasional patches
of tissue are met with, beautifully injected, while all around is a mass
of extravasation, and this remark applies especially to fatal subjects.
Prior to the above date, M. Gruby published an account in the Comptes
Rendus of some very successful injections which he had made by em-
ploying certain fluids, which he used separately, and which, when they
met, mutually decomposed each other, and deposited the coloring matter
in the vessels themselves.
He used saturated solutions of the chromate or bichromate of potash,
and of the acetate of lead: he directed that equal quantities of these
fluids should be used, first injecting all the chromate of potash, to the
extent of one half the quantity of injection supposed to be necessary,
into the vessels, and subsequently the same quantity of the acetate of
lead.
As soon as these fluids meet, they decompose each other; the acetic
acid of the acetate of lead combining with the potash to form the
acetate of potash, which is set free, and the chromic acid of the chrom-
ate of potash combining with the lead to form the beautiful chromate of
lead, which is deposited in the vessels.
The reports which had reached me were highly confirmatory of
M. Gruby’s success with these fluids, and having seen Mr. Bowman’s
preparations of the kidney injected on this principle, and with the like
materials, I determined to employ them. My experiments, however,
were most unsatisfactory, for, having injected a terrier puppy, a dis-
section of several hours was required to ascertain whether I had suc-
ceeded in injecting any part or not, and my best reward consisted in a
patch of capillaries, slightly painted of a pale yellow color, and en-
tirely wanting that roundness and fulness, characteristic of a good in-
jection.
I next procured a human foetus, and injected it, with precisely the
same results.
On making inquiry of Mr. Bowman, touching the ordinary success
which had attended his experiments, and the experiments of others, so
far as he knew, he told me that I appeared to have met with fair ave-
rage results, for that the labor of dissecting, consequent on using these
fluids, was always great, and that the operator must consider himself
well rewarded for two or three days’ work, by finding a microscopic
bit well injected.
From this narration of failures, it will be evident that the fluids rarely
meet in the vessels, otherwise the color would be necessarily precipitated.
With a view to see exactly what took place, I determined to inject a
piece of intestine, in which the whole process would be under my in-
spection. I placed pipes in the mesenteric veins, and secured all the cut
vessels in the usual manner; I then proceeded to throw in the chromate
of potash, and found that the potash would not wait for the lead, but
came out instantly through the parietes of the vessels as fast as it went
in, and in one broad stream covered the table. I repeated this experi-
ment a number of times, but with the same uniform result; on some
occasions I threw in the lead also, and as the vessels were moist with
the chromate, the slight painting I have mentioned took place ; but as
only equal quantities of the two fluids produce the best color, the ex-
cess of the lead was useless.
Having observed, at this stage of my experiments, that the precipi-
tated chromate of lead is remarkably fine and soft, I determined to use
it, in lieu of vermillion, with size; and although the success was far
greater than when I used the fluids separately, the results were in no
way superior to the old red injection.
The principle involved in M. Gruby’s use of these fluids: that,
namely, of forming the color within the vessels themselves, appeared to
be undeniably good, notwithstanding it had so signally failed in my
hands, and, as far as I could learn, in the hands of all those persons
who had hitherto employed it; and I had no doubt that if I could suc-
ceed in giving some consistence to the fluids, the results might prove
more satisfactory. For this purpose, size would not do, as it is rarely,
when bought, much too strong for use, and it would not bear further
dilution. 1 therefore procured the highly concentrated preparation em-
ployed by pastry cooks, and sold by grocers, under the name of gela-
tine. The following is my formula for the double injection with this
material:—
Sat. solution of bi-chromate of potash, eight fluid ounces ; water,
eight ounces : gelatine, two ounces.
Sat. solution of acetate of lead, eight fluid ounces; water, eight
ounces ; gelatine, two ounces.
Thus, gelatine, two ounces, are dissolved in sixteen ounces of fluid,
and kept and used separately as before ; but the success consequent on
lhe addition of the gelatine was quite extraordinary ; the vessels were
all full ami round, and there was no extravasation ; and for reasons
hereafter to be explained, the microscope revealed scenes so rich in
depth, color, and beauty, as to exceed the best red injections I have ever
seen.
With this form of injection I have never failed; I have injected three
foetal subjects so minutely, that the capillaries of the skin, and of every
tissue, were perfectly injected. Amongst the best specimens I obtained,
1 may mention injections of the papillae of the lips, gums, and tongue;
of the pulps and capsules of the teeth ; of the conjunctivae and other
tissues of the eye ; of the mucous membrane of the nose and cellular
tissue; fascia; periosteum, &c.; ceruminous glands, lymphatic glands,
and thyroid glands ; pericardium, auricles of the heart, vasa vasorum,
particularly of the aorta and vena cava, and the vessels of all the nerve
sheathes. In fine, one foetus occupied me in dissecting, ten hours a day,
for two months, and was scarcely half finished at the expiration of the
time.
Having described the success attending the use of these injecting
fluids, I must now say how they are to be mixed and used, as every-
tliing depends on care in these respects.
Each parcel of gelatine must be dissolved in the water only, (eight
ounces,) and in a separate water-bath. The water-baths I employ, con-
sist of two earthen pans, such as are applied to a child’s chair, and ca-
pable of containing about one quart each; these are fitted to two tin
kettles, the broad flange of the earthen pan resting on the rim of the
kettle, the pan covered with a common saucepan lid. The kettles
should be furnished with a bail of iron wire, like that of a glue-pot, or
pitch-kettle.
The gelatine is to be slowly dissolved in the eight ounces of water ;
when this is accomplished, the eight fluido unces of bi-chromate are to
be added to the gelatine in one pan, and the eight fluid ounces of acet-
ate of lead to the gelatine in the other; each should be well mixed by
stirring with a glass rod, a separate rod being used for each solution,
lest the chromate of lead should be precipitated.
The fluids thus prepared, must then be strained through fine flannel
(using a piece for each fluid) into other vessels, the earthen pans
cleaned, and the fluids returned to them. The injections are now ready
for use, and must be kept at a temperature of about 90° by the warm
water contained in the kettles.
Directions foi' Using the Injection.—The best subject to inject is a
foetus, as there are no cut vessels by which the injection can escape.
A pipe, with a stop-cock attached, should be firmly tied in the umbilical
vein, leaving the arteries open until the yellow injection makes its ap-
pearance, when they should be secured. It is most essential that, for
this injection, the subject be warmed through by immersion in warm
water, the temperature of which must not be higher than 90°, or cor-
rugation of the tissues will take place; it will require from one hour to
two hours to accomplish this, and the temperature must be maintained
until the injection be completed. The whole sixteen ounces of the
potash preparation of gelatine must now be used, care being taken that
its temperature never exceed 90°. Some manipulators deem care of
little import in the early stage of injecting, and throw in the first few
syringefuls rapidly, and only exhibit caution when the subject begins
to fill. In my experience, this is an error; and he who would suc-
ceed must be equally careful and patient throughout. It is my prac-
tice to let the piston descend so slowly, that it can scarcely be seen to
move.
Having used the whole of the first preparation, the acetate of lead
must be used, when the color will instantly be formed, and give the
operator some idea of his progress.
The temperature of the subject must be kept up, and a fresh batch
of injection made and strained as before. In about half an hour the in-
jection may be resumed, and the bi-chromate again claims precedence ;
but only half the quantity need he used now, followed by an equal
quantity of the lead. At this point the stop-cock should be turned, and
the subject again allowed to rest for half an hour; the remainder of the
injections may then be used, and after this, in all probability, the sub-
ject will require another batch. The manipulator who employs for the
first time, as much injection for a fcetus as I have already directed to be
used, and who experiences the great resistance opposed to the trans-
mission of the last several syringefuls, especially as the body will by
this time be swollen and tense to an amazing degree, will feel somewhat
surprised to learn, that if he suspend the operation for an hour, keeping
up the temperature in the meanwhile, he will be able to throw into the
subject twenty or thirty ounces more with comparative ease, and have
the pleasure of seeing many isolated congeries of vessels of the skin
gradually approaching each other, and finally anastomosing most per-
fectly, while the tension of the body will be so great, that if the piston
be pressed completely down, and the hand withdrawn, it will gradually
rise, and the same may, with care, be repeated several times, without
causing extravasation.
Towards the conclusion of the process, the injections should be thrown
in alternately; and this should be continued, notwithstanding the pro-
digious distortion of the body, as long as the injection is felt to flow in
the vessels. To inject a fetus well, on this plan, will occupy from four to
five hours. The operation finished, the body should be thrown into
cold water, and should not be dissected until the next day.
The. Dissection,—Will soon reveal what has become of the injection,
and is altogether a disagreeable and difficult task. It will be found that
nearly all the gelatine and acetate of potash have transuded and sepa-
rated the tissues widely from each other, and that the blood has been
diluted, and intimately mixed with the gelatine, which is colored by it.
The majority of preparations thus injected, require to be dried, and
mounted in Canada balsam. Each preparation, when placed on a slip
of glass, will necessarily possess more or less of the colored infiltrated
gelatine, which, when dry, forms, together with the different shades of
the chromate of lead, beautiful objects, possessing depth and richness of
color. The gelatine also separates and defines the different layers of
vessels. By this injection, the arteries are always readily distin-
guishable, by the purity and brightness of the chromate of lead within
them, while the veins are detected by the altered color imparted by the
blood.
Those preparations which require to be kept wet, can be preserved
perfectly in my B fluid, specific gravity 1,100; the A fluid destroys
them. I regret much that a gentleman, (now deceased,) Alexander Nas-
myth, Esq., for whom I prepared a great number of such injections, had
no faith in my preserving fluids at that time, and employed a chemist to
prepare a fluid for the preservation of these yellow injections, which
has quite destroyed some of the most beautiful preparations I have ever
seen, while some of the fellow parts in my possession, are as perfect
now as they were seven years ago.
I would recommend, that the slips of glass employed for the dry pre-
parations be instantly inscribed with the name of the preparation, written
with a diamond, for, when dry, it is very difficult to recognise one pre-
paration from another, until the operator’s eye be educated to the effects
of this chemico-gelatinous injection. Where so much wet abounds,
gummed paper is apt to come off.
When dry, it is sufficient for the purpose of brief examination by the
microscope, to wet the surface of a preparation with clean oil of tur-
pentine ; immediately after examination, it should be put away care-
fully in a box, to keep it from the dust, until it can be mounted in Ca-
nada balsam.
The bi-chromate of potash is greatly superior in color to the chromate,
which yields too pale a yellow; and subsequent experience has con-
vinced me that the acetate of potash frequently effects its liberation by
destruction of the capillaries, and this, even long after the preparations
have been mounted in Canada balsam ; perhaps this may be owing to
some chemical action of the acetate of potash upon them.
I would suggest the substitution of the nitrate for the acetate of lead,
as we should then have, in the liberated nitrate of potash, a valuable
auxiliary in the process of preservation.
Although highly desirable, as the demonstrator of the capillaries of
normal tissues, I do not think this kind of injection fitted for morbid
preparations, the infiltrated gelatine producing appearances of a puzzling
kind, and calculated to mislead the pathologist.
In preparing portions of dried, well injected skin for examination by
the microscope, 1 have tried the effect of dilute nitric acid, as a corroder,
with very good results. But probably, liquor potassae would have an-
swered this purpose better.
When size injection is to be employed, colored either with vermillion
or the chromate of lead, the animal should be previously prepared by
bleeding, to empty the vessels ; for if they be filled with coagulated
blood, it is quite impossible to transmit even size, to say nothing of the
coloring matter. Hence the difficulty of procuring good injections of
the human subject.
But with the “ chemico gelatinous” injection no such preparation is
necessary ; and success should always be certain, for the potash liquefies
the blood, while constant and long-continued pressure by the syringe
drives it through the parietes of the vessels into the cellular tissue. Tne
large quantity of infiltrated blood—the invariable concomitant of my pro-
cess—characterizes this from all other modes of injecting, and is a dis-
tinctive feature of these preparations.
I find that a very superior preparation of gelatine is now on sale at
at the grocers’ shops, nearly equal in appearance to isinglass. From its
apparent purity, I am led to infer that a less quantity of it would suffice
for the number of fluid ounces mentioned above.
The only preparations of gelatine extant when I made the experiments
recorded in my paper, contained a large quantity of dirty, insoluble
gluten, from which defect I venture to assume the French gelatine
is free.—London Lancet.