EXAMPLE 4 



Preparation of a Wholemount of a Liver Fluke, 

 Using the Carmalum Stain of Mayer 



Although many people will be forced to rely on a supply house for their 

 material, much better preparations can be made if the living flukes are 

 obtained from a slaughterhouse. In this case, the flukes should be removed 

 from the liver, where many will be found crawling upon the surface if the 

 animal has been dead for some time, to a thermos flask containing physio- 

 logical saline solution at a temperature of about 35° C, to which has been 

 added a small quantity (approximately 1 g per liter) of gelatin. Flukes 

 can be transported alive for relatively long distances in this solution, and 

 every possible effort should be made to keep them alive until they have 

 been brought to the laboratory and are ready to be fixed. In the laboratory 

 the contents of the thermos flask should be poured into a dish and the 

 worms transferred individually to another large dish containing warm 

 physiological saline, where the last of the blood will be washed from 

 them. Better preparations will be secured if time is taken to anesthetize 

 the worms before fixing them, since most of the thick and opaque 

 mounts like those shown in Fig. 136 result from an endeavor to fix an un- 

 anesthetized worm that has contracted during the course of fixation. Liver 

 flukes are easy to anesthetize; the simplest method is to sprinkle a few 

 crystals of menthol on the surface of the warm saline solution and leave 

 the flukes in this for about % hr. Care should be taken that the worms 

 do not die in this solution and the process must be terminated when 

 their motions are exceedingly slow and consist only of occasional feeble 

 contractions rather than the active movements in which they were indulg- 

 ing when removed from the liver. 



While the worms are being anesthetized, preparations for fixing them 

 should be made. Take two sheets of %-in. plate glass, large enough so 

 that the number of worms that are to be fixed can be laid on them, and 

 place upon the lower plate two or three thicknesses of a rather coarse 

 filter paper or paper toweling. Blotting paper is too soft to be used for the 

 purpose, and a good filter paper is much to be preferred to a paper towel. 



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