22 FECAL DIAGNOSIS OP INTESTINAL PROTOZOA 



while their glycogen filled vacuoles, when present, turn 

 light or dark brown according to their mass. The nuclei 

 become more clearly defined as the iodin penetrates, espe- 

 cially in E. [Entamoeba] coli and E. dysenteriae [histolytica]. 

 They are detected with difficulty in this stain in E. [Endo- 

 limax] nana." (Kofoid, Kornhauser, and Swezy.) 



2. Cropper and Row's concentration method. This method 

 as modified by Boeck is as follows: "Take at least one gram 

 of the stool to be examined, place it with thirty cubic centi- 

 meters of normal saline solution in the mixing glass and stir 

 for at least ten minutes with an electric mixer such as is 

 used at soda fountains in mixing drinks. At the end of ten 

 minutes, while still stirring, add five cubic centimeters of 

 ether and stir two or three minutes longer. Pour the 

 emulsion into a separatory funnel and allow to stand for at 

 least five to seven minutes, during which the cysts will 

 settle to the bottom in the saline solution and debris will 

 float in the ether above. The funnel used for this separation 

 has a funnel-shaped bowl with steep sides contracting to a 

 narrow neck above the turncock. 



At the end of this period of standing, the saline solution, 

 about fifteen cubic centimeters, is drawn off at the bottom 

 of the separatory funnel into a centrifuge tube of a capacity 

 of fifteen cubic centimeters, and is centrifuged for three 

 minutes at 1600 revolutions per minute. The supernatant 

 fluid is then drawn off and the residue is examined micro- 

 scopically for the cysts. At this time a drop of neutral red 

 is applied to a small amount of this residue to procure a 

 sharper contrast between the cysts and the surrounding 

 debris. By this method a faecal examination can be com- 

 pleted in twenty-five to thirty minutes." 



3. Schaudinn's alcoholic sublimate iron-haematoxylin 

 method, a. Prepare a fixing solution as follows: Saturated 

 solution of mercuric chloride in distilled water, 200 cc.; 



