COLLECTION, CULTIVATION, OBSERVATION 723 



dling coverglasses, as they are easily broken. Large free-living 

 Protozoa do not frequently adhere to the glass, since there is not 

 enough albuminous substance in the culture fluid. If a small drop of 

 fresh egg-white emulsified in sterile distilled water is smeared on the 

 coverglass very thinly with the tip of a clean finger, before mounting 

 material for smear, more specimens will adhere to and remain on the 



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Q) C3 % 



Fig. 335. 1, Sphaerita in a stained trophozoite of Entamoeba coli; 

 2, Nucleophaga in a stained trophozoite of lodamoeha butschlii; 3, 4, fresh 

 specimens of Blastocystis hominis; 5, 6, stained Blastocystis hominis; 7, an 

 epithelial cell found in faeces; 8, a polymorphonuclear with three ingested 

 erythrocytes. X1150 (Kudo). 



coverglass upon the completion of the preparation. Let the smear 

 lie horizontally for 5-10 minutes or longer. 



Parasitic Protozoa live in media rich in albuminous substances, 

 and therefore, easily adhere to the coverglass in smear. Make uni- 

 formly thin smears on coverglasses. If the smears are made from 

 dysenteric or fluid stools, they should be fixed almost immediately. 

 Smears made from diarrhoeic or formed stools by emulsifying in 

 warm salt solution, should be left for a few minutes. In any case, do 

 not let the smear become dry except a narrow marginal zone. 



The smears are fixed next. The most commonly used fixative for 

 Protozoa is Schaudinn's fluid. This is made up as follows: 

 Cold saturated mercuric 



bichloride (6-7%) 66 cc. 



Absolute or 95% alcohol 33 cc. 



Glacial acetic acid 1 cc. 



The first two can be kept mixed without deterioration, but the acid 

 must be added just before fixation. Fix at room temperature or 



