The Preservation of Material. 197 



the body, and no clogging of the vessels need be feared. The fluid 

 ay usually be observed running in the cannula, and, of course, falling 



the reservoir. Finally, there are characteristic changes in the body. 

 ie abdomen becomes greatly distended, the subcutaneous tissue 

 rollen, the eyes protrude, and there is usually more or less frothing at 

 e nose. Leakage, either in the area of the incision or at the nose, is 

 metimes a sign of too much pressure. In the former case the leakage 

 frequently behind the cannula, and may be stopped by artery forceps. 



the latter case there is no recourse but to confine the fluid to the 

 .sal cavity by tying the nostrils. 



After the embalming process the rubber tube is disconnected from 

 e cannula, the latter being left carefully in place. The animal is then 

 t aside for twenty-four hours in an upright position. After this it is 

 idy for injection. 



The injection mass may be made by mixing ordinary starch and 

 iter to the consistence of thin cream; then adding a finely-ground 

 loring material, such as vermilion or a very small quantity of carmine, 

 lere is some advantage in using a 5% formalin instead of water alone 

 making up this mass, the arteries having afterwards a brighter appear- 

 ce, which is doubtless due partly to better preservation and partly to 

 a fixing of the starch in the vessels. The mass must be thoroughly 

 ained before use, in order to avoid the presence in it of particles which 

 i too large to go through the cannula. The injection is made with 

 yringe, the latter being provided with a rubber tube of the same kind 

 that used in the embalming process. The mass is sent in by applying 

 jentle, even pressure, and it is sometimes advantageous to allow the 

 ection to run backward and forward in the tube, each time applying 

 ittle more pressure. When the vessels have been filled in this way, 

 > tube is clamped. By drawing on one cord of the ligature the knot 

 loosened sufficiently to withdraw the cannula, and by keeping a 

 jer pressed on the end of the vessel, the knot may then be drawn 

 (it without loss of injection. 



It sometimes happens, despite ordinary precautions, that the cannula 

 :omes clogged either with settled starch or with coagulated blood, 

 this case it may be easily removed, cleaned, and replaced. The same 

 inula should always be used. 



Material prepared according to the directions given above will keep 

 efinitely, provided, however, that precautions are taken to avoid con- 

 lination from the surface. These are especially necessary in view of 



thick coating of hairs. It is a good plan, therefore, to sponge the 

 tnal with a preserving fluid which will penetrate the coat imme- 

 tely, or if many specimens are being prepared, to immerse the whole 

 tnal for a moment. A suitable fluid for this purpose is formalin- 

 >hol, made by adding 2% of formalin to a mixture of equal parts of 

 inary spirit and water. The alcohol ensures immediate penetration 



assists the formalin in preservation. The fluid should be squeezed 



of the coat as much as possible. The presence of a considerable 

 ntity is not harmful, unless, after the dissection has begun, the fluid 

 ild gain access to the tissues and destroy the effect of the glycerin 

 he embalming fluid. 



