TECHNIQUE. 43 



METHODS OF STAINING MATERIAL CONTAINING 

 AMCEB^E. Owing to the very delicate structure of 

 amoebae any method of fixation and staining which 

 may be adopted undoubtedly causes some change in 

 size and morphology and one's object should be to 

 use methods which will obviate, as far as possible, such 

 artificial changes. For the best results in the study 

 of the morphology of the nucleus of amoebse, as well 

 as other Protozoa, and more especially the changes 

 occurring in this structure during multiplication, fixa- 

 tion of the wet specimen with osmic acid vapor or 

 sublimate alcohol, followed by staining while the 

 specimen is still wet, is essential, although air-dried 

 specimens, which are afterward stained, are sufficient 

 for ordinary work. I was able to confirm all the 

 essential details of Schaudinn's work upon Entamoeba 

 histolytica and Entamoeba coU in air-dried smears of 

 material containing these parasites, stained with 

 Wright's modification of the Romanowsky stain, 

 although only after months of study and the examina- 

 tion of many thousands of preparations. Had the 

 wet fixing and staining methods been used at that 

 time much labor would have been saved and the mitotic 

 division of the nucleus would have been demonstrated. 

 In making stained preparations it is first necessary to 

 fix upon a slide or cover glass the material to be ex- 

 amined. For this purpose numerous fixing mixtures 



