STANDARD METHODS AND REAGENTS 471 



in xylol or chloroform, infiltrated, and finally embedded in paraffin. 

 Rarely the material is embedded in celloidin. 



The staining of sectioned tissue containing protozoa does not 

 differ essentially from the staining of smears except that the 

 sections are relatively much thicker than the smears so that longer 

 intervals of time must be allowed for such procedures as the 

 replacement of water with alcohol or vice versa, impregnation with 

 the mordant or the stain, and clearing. Sections to be used for 

 pathological study are usually stained with Delafield's hema- 

 toxylin ^^ and eosin. For cytological details, particularly of the 

 parasites, use Heidenhain's iron-alum-hematoxylin or Mayer's 

 hemalum. In studying tissues which contain blood-inhabiting 

 protozoa it is many times worth while to stain a few sections with 

 Giemsa's stain in order to get the Romanowsky efifect. The slides 

 are passed through descending grades of alcohol to water and are 

 stained for from one to twelve hours in freshly diluted (one in 

 ten) Giemsa's stain. Do not pass the slides through the alcohols 

 to return to xylol as the stain will be extracted. Use a number of 

 mixtures of xylol and acetone (5:95, 30:70, 50:50) before going 

 into pure xylol. 



Cultivation Methods 



Anwchce. The cultivation methods which are in general use for 

 E. histolytica are treated in Chapter XIX. These methods appear 

 to be suitable, with at most only slight modifications, for the cul- 

 tivation of other entozoic amoebae of man and lower animals. In 

 this connection see the papers of Barret and Smith (1924 and 

 1926), Chiang (1925), Dobell (1926), Drbohlav (1925, 1925a, 



" Delafield's hemutoxylin 



Hematoxylin (crystals) 4.0 gms. 



Ethyl alcohol (95%) 25.0 c.c. 



Dissolve hematoxylin in alcohol and add, 

 drop by drop to 



Ammonia alum (saturated solution) 400.0 c.c. 



Expose to light and air in an unstoppered 

 bottle for three or four days. Filter, and 

 add: 



Methyl alcohol (90%) loo.o c.c. 



Glycerin lOO.o c.c. 



Allow solution to stand uncorked in the 

 light until it darkens in color and is "ripe" 

 (Hematoxylin oxidized to hematin). 



