6 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 122 



dehyde solution plus nine parts water and specimens. Buffer in 

 about one day by adding one-half teaspoon of borax powder per quart 

 of solution. Open the abdominal cavity and the gut to expose them 

 to the preservative. Such structures as fur and feathers, which may 

 be difficult to remove later, should be removed at this time. The 

 viscera, most scales, and many other undesired parts preferably are 

 removed after staining to prevent loss of small bony structures. 



The best preservation results from killing the animal in the fixing 

 solution. Dead but unpreserved animals should be fixed without 

 delay. Whether they will yield satisfactory specimens depends upon 

 the length of time they have been dead and upon their prior treat- 

 ment. Short delays, even of less than an hour after death, and expo- 

 sure to high temperature before fixation msij result in specimen 

 contamination, decomposition, and noticable connective tissue break- 

 down. The destruction of tissues continues slowly when the specimen 

 is under refrigeration and, to some extent, when the specimen is frozen, 

 although some specimens that were frozen for several days have turned 

 out satisfactorily without preservation. 



Small specimens that have died immediately prior to the enzyme 

 treatment sometimes result in good preparations without preservation, 

 but fixation is more reliable. If they are not fixed, they shoidd be 

 eviscerated and subjected to the clearing process, beginning with step 

 3 without delay. 



Specimens stored in isopropyl or ethyl alcohol require no further 

 preliminary preparation. Those that were initially fixed in alcohol 

 or that exhibited spoilage before formaldehyde fixation may disinte- 

 grate in digestion. Specimens damaged, twisted, or distorted when 

 fixed become good cleared examples that often are not distinguishable 

 from those that were preserved in a more normal position; they usually 

 are chosen for clearing in order to retain the better specimens for other 

 purposes. 



2. Pour off formalin or any preserving solution containing the odor 

 of formaldehyde and soak the specimen in repeated changes of water 

 until the formaldehyde is removed. Formaldehyde as well as some 

 metals and some apparent formaldehyde derivatives that are not 

 soluble in water or alcohol inhibit the enzyme reaction (see further 

 comments in step 6). If the specimen is not to be cleared immedi- 

 ately, it should be stored in a 70 percent solution of ethyl alcohol. 



3. Bleach the specimen in a solution of 10 to 20 percent stock 

 hydrogen peroxide and 80 to 90 percent stock potassium hydroxide. 

 Because the reaction is enhanced by light, it may be placed in a 

 transparent container over a light box or beneath a lamp. Body 

 cavities containing heavily pigmented membranes should be opened 



