104 THE AMERICAN MONTHLY [April, 



Method of Demonstrating Living Trichinae. 



By ALGERNON S. BARNES, Jr., M. D. 



ST. LOUIS, MO. 



The living trichina, or pork worm, makes an attractive slide, 

 and never fails to attract attention. An old cat or rat is killed, and 

 the muscle from between the ribs, also the diaphragm and 

 muscles of the thigh, are extirpated. A piece is nipped from 

 each of the specimens, and placed between two slides, which are 

 pressed together and examined under the microscope with about 

 a one-inch objective. 



If the trichinte are found to be present in their cysts, a piece 

 of the muscle the size of a pea is placed in the following solution 

 in a small bottle : 



Pepsin, .... gr. iii 



Water, . . . . 311 



Hydiochloric acid, . . m. 11 



As this is to duplicate the process of digestion, the fluid must 

 be kept at body temperature, preferably in the pants pocket, or 

 in a warm oven. The fluid is to be shaken every little while ; 

 in about three hours, sometimes less, the meat will be dissolved, 

 as well as the cyst which contains the trichinge. The fluid is 

 then poured into a conical-shaped glass to allow the trichinae to 

 settle to the bottom, which operation will consume about ten 

 minutes. A pipette is then introduced into the glass near the 

 bottom, and the contents placed in a glass cell, which should be 

 large. This cell is then placed under a dissecting microscope, 

 and the trichinae taken out by means of a pipette and placed in 

 clear water. They are again picked out of the clear water by 

 the same method, and placed in a drop of pure water in the 

 centre of a glass, cement cell, or in a live-box, and a few minutes 

 allowed for the worms to settle to the bottom. A cover is now 

 put on and sealed with white vaseline. It is now ready for examina- 

 tion on a hot stage under the microscope, where the worm may 

 by enlivened at will by the heat. 



I have found that about three trichinae in a cell are sufficient, 

 for when they get lively they are hard to keep in the field and in 

 focus. If a permanent mount should be wanted of isolated worms 

 they are finally placed in a drop of glycerin instead of water in 

 a cell and sealed with cement. The worms will be found 

 uncurled in the glycerin, which kills them. 



The meat may be kept in pure glycerin for several years, but 

 of course the worms will be dead and may be dissolved out by 

 this process. 



An Aluminum Microscope. — A microscope recently made 

 of aluminum weighs only 2 pounds 10^ ounces. The screws are 

 of brass, the fine adjustment of steel, and the nose-piece of German 



silver. The .same instrument in brass weighs 7 pounds 13 ounces. 



