TECHNIQUE. 



THE parasitic amoebae of man may be studied in 

 the living condition, in stained smears of material 

 containing them, and in stained sections of tissue. Each 

 of these methods has its advantages, but for diagnosis 

 and for the study of the vital activities of these 

 parasites the examination of fresh material is the 

 most satisfactory. It is never necessary for diag- 

 nostic purposes to stain amoebae nor is it essential for 

 the differentiation of species. It is very difficult to 

 stain these organisms and even with the utmost care 

 it will often be found that scores of preparations 

 will have to be examined before a satisfactory one 

 is obtained. As fixing and staining the organisms 

 often cause them to assume appearances very unlike 

 those observed in living specimens, it is my belief that 

 stained preparations should never be depended upon 

 for diagnosis except in the hands of an expert. 



However, the use of stained smears is necessary 

 in following out the nuclear changes during the life 

 cycle of these organisms, for while in the living speci- 

 mens such changes may be observed, they are much 

 more definitely marked in the stained preparations. 



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