Part 4 — CHAPTER VII. PRESERVATION OF SPECIMENS OF MORBID ANATOMY.

Many valuable and interesting pathological specimens are continually being lost, from a want of knowledge, or a careless neglect on the part of the physician. That the fullest benefit may result from a post-mortem examination, any rare or interesting specimen should be carefully preserved. Should the physician feel no interest in forming a cabinet of morbid anatomy for himself, he should then deposit the specimen in the anatomical museum of some medical school, where it may be permanently preserved, and the profession thus benefited.

All specimens of soft tissues designed for preservation, should first be soaked in water which is changed daily, until all blood is removed. If the weather be warm, it will be necessary to add to the water each time, either a small proportion of alcohol, or some antiseptic, as carbolic acid, chloride of zinc, corrosive sublimate, or common salt.

After all blood is removed, the specimen may be put into alcohol of a strength proportionate to the size of the specimen, and then allowed to remain until thoroughly “cured.” Small specimens are dried up, shrunken and nearly spoiled in many cases, by the use of too strong alcohol, while on the other hand, large ones, by diluting the alcohol with the large amount of water contained, would be likely to spoil in a weak preparation. Large specimens, particularly in warm weather, should have deep incisions made at a few points, for the better penetration of the preserving fluid.

Before being permanently put up, the specimen should be carefully trimmed, and everything interfering with the best display of the essential point removed.

327While either of the antiseptics mentioned above will answer for “curing” a specimen, for permanent suspension, there is no substitute for alcohol. Other fluids may preserve, but they will also become turbid, throw down a precipitate, and in cold weather are liable to freeze, while from their high specific gravity, many light specimens will float on or near the surface. If the specimen has been thoroughly “cured” before suspension, very dilute alcohol will answer for that purpose: equal parts of pure water and alcohol of ninety-five degrees, in all except the larger specimens, being abundantly strong. Delicate, light specimens will sometimes float in such a dilution, in which case it should be made stronger.

The best form of anatomical jar is made with ground glass stoppers, with a hook on the under side of the latter for suspending the specimen. Although expensive, these jars, by effectually securing the alcohol from evaporation, as well as from the greater facility with which the spirits may be changed, which will sometimes be required, will give better satisfaction than any other.

Where the common jar without a stopper is used, great care will be required in closing up, to prevent loss by evaporation. There should first be prepared a circular plate of thick sheet lead, to rest on the top of the neck of the jar. The specimen having been suspended by a string, carried through by a large needle, and at two different points, is to be fastened to the disk of lead by means of two holes, punched by an awl, about half an inch apart, near the centre. The portion of string above the lead, with the holes also, should now be carefully covered with sealing-wax, otherwise, by capillary attraction, the alcohol will keep the bladder covering continually wet, and finally rot it out. Over the lead is now to be stretched a piece of moistened bladder, and wound with twine around the neck of the jar. When dry, this is to be covered with a coat of black varnish; this 328again when dry, being followed by a second layer of bladder and varnish.

Wet preparations should be kept where they may have a free exposure to sunlight. If placed in a dark closet, they become damaged in texture, and acquire a dark and unpleasant color; this is particularly the case with the ligamentous and nervous tissues.

Dr. Brunetti of Padua, who has invented a new process for preserving certain kinds of specimen, and who received a gold medal some years ago at the Paris Exposition, gives the following particulars of his method:

“The process comprises four several operations, viz.: 1, the washing of the piece to be preserved; 2, the degraissage, or eating away of the fatty matter; 3, the tanning, and 4, the desiccation.

“1. To wash the piece M. Brunetti passes a current of pure water through the blood-vessels and the various excretory canals, and then he washes the water out by a current of alcohol.

“2. For destroying the fat he follows the alcohol with ether, which he pushes, of course, through the same blood-vessels and excretory ducts; this part of the operation lasts some hours. The ether penetrates the interstices of the flesh and dissolves all the fat. The piece, at this point of the process, may be preserved any length of time desired, plunging it in ether, before proceeding to the final operations.

“3. For the tanning process M. Brunetti dissolves tannin in boiling distilled water, and then, after washing the ether out of the vessels with distilled water, he throws this solution in.

“4. For the drying process Dr. Brunetti places the pieces in a vase with a double bottom filled with boiling water, and he fills the places of the preceding liquids with warm, dry air. By the aid of a reservoir, in which air is compressed to about two atmospheres, and which communicates 329by a stop-cock and a system of tubes, first to a vase containing chloride of calcium, then with another heated, then with the vessels and excretory ducts of the anatomical piece in course of preparation, he establishes a gaseous current which expels in a very little time all the fluids. The operation is now finished.

“The piece remains supple, light, preserves its size, its normal relations, its solid elements, for there are no longer any fluids in it. It may be handled without fear, and will last indefinitely.”

For the preservation and hardening of tissues for microscopic examination—as sections of tumors, glands, membranes, spinal cord or brain, etc.—Müller’s fluid may be employed, which is prepared as follows: bichromate of potassa, 75 grains; sulphate of soda, 35 grains; dissolved in six ounces of water. The specimen should be suspended in this fluid until sufficiently hardened to permit of a satisfactory examination.

Preparation of Bones.

Pathological specimens of bones, may be prepared either by boiling or maceration. The method by boiling should be employed, however, only where the texture of the specimen is firm and solid, as in cases of united fracture, etc.; and in these cases, care will be required to avoid injuring the specimen by too long exposure to the process. Maceration, however, is the better method for all cases, and the only one to be employed in cases where the bone is softened by caries or necroses.

The specimen having been roughly stripped of the soft tissues, is to be thrown into a vessel of water, the latter being changed every day, as long as it becomes colored by the blood. It is now to be left until the putrefactive process 330has so softened the tissues that they may be easily removed, when, after being thoroughly washed in soda water, it may be dried and mounted. If the weather be cold, it will be absolutely important that the macerating be conducted in a warm room, else the process will be so slow as to convert the tissues into a form of adipocere, quite arresting the putrefactive process, and greatly damaging the specimen in its beauty and value.

In this connection, it may be observed that bones from a subject that has been injected with chloride of zinc, can never be successfully macerated, the zinc having a sort of tanning effect upon the tissues, which enables them to resist the putrefactive process. Boiling is the only method by which such specimens can be cleansed.

Where a bone has been properly macerated and dried, and especially if from a young subject, it will be found white and quite free from grease; but when taken from old subjects, or when prepared by boiling, it may be required to be subjected to a bleaching process for removing the grease and improving the color. By exposure to the sun, with frequent washing in chlorine and soda water, the appearance of the specimen may be greatly improved, or what is still better, by covering the specimen for a few days in sulphuric ether, which will effectually dissolve out all the grease, and then washing and exposing to the sun for a few days, it will be left beautifully white and clean.

For permanent preservation, the specimen should finally be mounted on a block or board, in such a manner as best to expose its interesting points.

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