APPENDIX 



The Preservation of Material^ 



THE method commonly used In the preparation of material for 

 dissecting purposes consists in first embalming the body with 

 suitable preserving fluids; afterwards filling the arteries with a 

 coloured injection mass, so that they are more easily traced. The 

 objects served by embalming are: (1) preserving the body from de- 

 composition for a sufficient length of time to complete the dissection ; 

 (2) keeping the body as nearly intact as possible; and (3) having 

 the organs in good condition for study. The point last mentioned 

 is an important one, since much depends on having the parts of 

 the animal in such condition that they are easily and comfortably 

 handled, and also easily observed. The desired results are accom- 

 plished, first, by introducing the preserving fluid through the blood- 

 vessels, instead of by immersing the animal, as was formerly the 

 practice ;2 secondly, by using in the preserving fluid such materials 



^The methods here given apply only to the preservation of specimens for 

 ordinary dissection, either singly, or in numbers for a laboratory course; with a 

 few observations on the difficulties which are likely to be experienced. Especially 

 in the matter of injections, the student who has acquired some knowledge of the 

 vascular system will be able to make complete injections of the portal system and 

 also satisfactory injections of the systemic veins, though the latter are somewhat 

 more difficult on account of the presence of valves in the vessels. Finer vascular 

 injections and injections of the lymphatic system according to the directions given 

 in the anatomical text-books may also be suggested. 



Owing to imperfect preservation of the contents of the digestive tube, 

 examination of the inner wall in embalmed animals does not usually reveal its 

 essential features. It is well to have at hand a demonstration specimen prepared 

 as follows: Remove stomach and intestines from a freshly killed animal. Wash 

 out the parts with weak salt solution. Fill, without distending, with 3 per cent 

 bichromate of potash, formalin-bichromate, or any of the standard fixing agents, 

 and tie the ends. Immerse the parts in the solution, and after a time examine 

 by slitting them lengthwise. 



2For sometimes convenient but less uniform preservation of small mammals 

 ordinary immersion methods may be employed, the animal being placed in a 

 preserving solution after making small incisions in the thoracic and abdominal 

 walls. Formaldehyde solutions of 2 per cent or better, and graded alcohols be- 



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