DETECTION OF THE PARASITES 



749 



(i) For an ex tempore preparation fix the amosbse by running a drop of a 

 1 per cent, solution of chromic acid under the cover-glass : then stain by 

 running in a drop of alum-carmine. 



(ii) For permanent preparations several methods have been recommended. 



FIG. 353. Amcfba coli. (After Losch.) 



A. Bertarelli recommends letting a drop of the liquid containing the 

 parasites dry on a slide, treating for 5 minutes with absolute alcohol very 

 lightly tinted with eosin, washing with a mixture of equal parts of alcohol 

 and xylol. then with xylol, and mounting in balsam. 



B. Spread the preparation carefully on the slide and, before it is dry, fix 

 for 10 minutes in an acetic-perchloride mixture (Schaudinn). 



Saturated aqueous solution of perchloride of mercury, - 100 c.c. 

 Absolute alcohol, 50 ,, 



Glacial acetic acid, - 5 drops. 



Wash for 10 minutes in alcohol containing a little iodine, then in 70 per cent, 

 alcohol for 30-40 minutes, and stain with Heidenhain's or Grenacher's haama- 

 toxylin or with hsematein and eosin. 



C. Fix for 10 minutes in Flemming's solution, wash in water, then in alcohol, 

 and stain with gentian- violet or safranin. 



D. To make out details of structure fix in Schaudinn's solution (B, ante) 

 or in alcohol and stain by one of the Romanowsky-Giemsa methods or with 

 Laveran's or Marino's stain. 



Sections. To prepare sections of the intestine or of the wall of an abscess 

 proceed by one or other of the following methods : 



A. Fix in Schaudinn's solution (B, ante) and stain with hsematein and eosin. 

 The amoebae are bright pink, the nuclei, violet. 



B. Fix as in A and stain with Heidenhain's iron hsematoxylin. The proto- 

 plasm of the parasite is hardly stained at all and the nucleus is outlined by 

 a blue-black line. 



C. Mallory and Wright's method. Fix in alcohol. Stain for 5 minutes in 

 a saturated aqueous solution of thionin : differentiate in a 1 per cent, solution 

 of oxalic acid for 30-60 seconds, watching the preparation under the micro- 

 scope and stopping the decolourization as soon as the nucleus assumes a 

 violet tint : wash : dry : mount. 



