NOTES FOR GUIDANCE IN MAKING PERMANENT 



PREPARATIONS 



Only very simple directions are here given, such as will 

 serve to aid students who have had no experience in prepar- 

 ing objects for microscopic examination to make preparations 

 when this is desirable for proper laboratory study. The best 

 simple directions for technique of this type may be found in 

 Guyer's Animal Micrology. Another excellent guide is 

 Galigher's Practical Microtechnique. 



For more elaborate work McClung's Microscopical 

 Technique or Lee's Microtomist's Vade Mecum are valuable. 



The steps taken in preparing total mounts include: 



1. Narcotizing or anesthetizing. 



2. Fixing or killing. 



3. Washing. 



4. Dehydrating and staining. 



5. Clearing. 



6. Mounting. 



Narcotizing. — A great many animals or animal parts may 

 be more easily fixed if first anesthetized. Many invertebrates 

 can be anesthetized by placing in a dish with an ample sup- 

 ply of water to which crystals of magnesium sulphate are 

 then added. As the crystals dissolve add more until anes- 

 thetization is complete. This method is especially good for 

 delicate hydroids. Other narcotizing agents which may be 

 used include the following: (l) chloretone, which may be 

 used similarly to the method given for magnesium sulphate. 

 Many small invertebrates may be transferred directly to 

 dilute solutions of chloretone, e. g., annelids (one part satu- 

 rated aqueous solution of chloretone to four to nine parts of 

 water) . For marine animals this solution should be made up 

 in sea water. 



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