Example 4 



Preparation of a Wholemount of a Liver Fluke, 

 Using the Carmalum Stain of Mayer 



Though many persons will be forced to rely on a supply house for their material, 

 much better preparations can be made if the living flukes are secured from 

 a slaughter house. 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 physiological saline solution 

 at a temperature of about 35° C, to which has been added a small quantity 

 (approximately 0.1 Gm. 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 which one sees in laboratories result from an endeavor 

 to fix an unanesthetized worm which has contracted during the course of fixa- 

 tion. 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 half an hour. Of course, one should not permit the 

 worms to die in this solution but should watch them carefully, terminating 

 the process when their motions are exceedingly slow and consist only of 

 occasional feeble contractions rather than the active movements in which they 

 were indulging when removed from the liver. 



While the worms are being anesthetized, preparations for fixing them 

 should be made. Take two sheets of quarter-inch plate glass, large enough so 

 that the number of worms which 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. The selection 

 of fixative must rest, of course, in the hands of the operator, but the author's 

 preference is for the mercuric-acetic-nitric mixture of Gilson. This has all the 

 advantages in sharpness of definition given by mercuric fixatives, while the 

 addition of nitric acid appears to render the flattened worms less brittle in 

 subsequent handling. Whatever fixative is selected, the sheet of filter paper is 

 saturated thoroughly with it, and the anesthetized worms removed from the 



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