Methods to preserve specimens in a museum..
Answers
Answer:
Euthanizing:
Reptiles require different euthanizing techniques than amphibians. Reptiles of any size are best euthanized by hypodermic injection with dilute Pentobarbital Sodium. Its commercial name is "Nembutal" and it is sold at some drugstores for veterinary use at a strength of one gram per cc. There are two types of Nembutal, a clear, thin liquid, and a dark brown, syrupy liquid (elixir). The clear type is preferable. Nembutal must be diluted with water before using. Dilutions should be one part Nembutal to nine parts water. Small snakes and lizards require only a few drops of this solution; large lizards and snakes (over two or three feet long), about one cc. or more. Death is usually very quick, often within a few seconds. Injection should be made either into or near the heart for rapid action. Reptiles can also be killed by immersion in warm water (110° F. ) for a few minutes. Turtles may require somewhat warmer water or longer periods of immersion. Do not leave the specimens in warm water for more than a few minutes after death. Injection of preservative directly into the heart may be used as an alternative method of euthanizing reptiles, but is generally less satisfactory than the above methods because death is slower and specimens often become contorted.
The most satisfactory method of euthanizing amphibians is by immersion in a solution of Chlorobutanol (Hydrous), sold commercially under the name "Chloretone." Euthanizing solution may be prepared by dissolving one level teaspoon of Chloretone powder in a gallon of water. This solution, if stored tightly capped, may be used over and over. Specimens should be placed in a container and completely covered with killing solution. If the solution is fresh the specimens will die in a few minutes; if it is old, more time will be required. Do not leave them in the solution for more than a few minutes after death. A very dilute (about 10%) solution of ethyl alcohol is also an effective killing agent and is used in the same way as Chloretone solution. Amphibians may be placed into the preservative alive. This is a rapid method of euthanizing, but almost always results in contorted specimens which are difficult to study. This technique should not be used except as a last resort.
Preserving Solutions
Formalin: If at all possible, formalin should be used for injecting and fixing specimens. Formalin is the commercial name of a solution of formaldehyde gas (CH20) in water. It is available at drugstores and chemical supply houses in the United States at a strength af from 38% to 40%. In Latin American countries, formalin may be purchased in many drugstores under the name "Formol" or "Formolina". Formalin must be diluted with water before it is used as a preservative. A strength of 10% formalin is best for most purposes. If the original strength is 40%, it should be mixed at a ratio af nine parts water to one part formalin. The advantages of formalin over other preservatives are: it is inexpensive, it is generally available, a small bulk af concentrated stock solution may be diluted as needed, and specimens almost never decay in it. Its principal disadvantages are: it has a very irritating odor, it is very poisonous and may cause skin irritation or rash, it has a tendency to make specimens become brittle if the solution is too strong, and tends to fade out certain colors rapidly, and it must be stored in rustproof containers. (Buffering of the 10% solution is recommended as formalin is slightly acidic. One buffering system that may be used is a mixture of monobasic and dibasic Sodium Phosphate, at 13 gm/gallon [Monobasic] and 24 gm/gallon [Dibasic]).
Alcohol. There is a high federal tax on ethyl alcohol which makes it a very expensive preservative unless it can be purchased by or through a university, museum or another such institution. It is usually sold at a strength of 95% (190 proof). For injection and fixing it should be used at full strength. For storage of reptiles it should be used in the proportion of 3 parts 95% alcohol to 1 part water. Alcohol which has been stored in open containers loses its strength rapidly due to evaporation. Strength may be tested with an alcoholometer. Specimens which have been fixed in alcohol should be carefully watched for signs of rotting. Alcoholic beverages, shaving lotions and Bay Rum contain ethyl alcohol. They should be used only in an emergency and without dilution. Liquor which is 100 proof is only 50% ethyl alcohol.
Answer:Any museum specimens are handled by the following steps:
1.)Reception
2.)Preparation
3.)Fixation
4.)Restoration
5.)Preservation
6.)Presentation
Explanation: