The Parasitology of Pyorrhcea alveolaris. 187 



Microscope, and the presence or absence of amoebte and other 

 organisms recorded. At the same time as the observation prepara- , 

 tion is made, a drop or two of the emulsion is spread out on a 

 perfectly clean cover-glass, which is at once dropped, film-side 

 downwards, into Schaudiun's fluid. After fixation, the prepaia- 

 tion is passed through 30, 50, 70 and 80 p.c. alcohol to absohite 

 alcohol, half an hour in each strength being best. From absolute 

 alcohol the preparation is now passed back through the various 

 grades of alcohol (half an hour in each) to distilled water. It is 

 next placed in 2 p.c. iron-alum solution over night. Next day it 

 is placed in 1 p.c. hematoxylin for twenty-four hours, and is then 

 differentiated by immersing in 2 p.c. iron-alum, the decolorization 

 being watched by means of the Microscope till the nuclei are 

 sharply differentiated. The preparation is washed, and passed 

 through the ascending grades of alcohol (fifteen minutes in each), 

 and then cleared with xylol and mounted in balsam. Staining 



Fig. 1. — Glass capillary pipette used for collecting material from 

 pyorrhceal pockets, x two-thirds. 



by means of Giemsa, after wet fixation with methyl-alcohol, was 

 tried in a number of cases, but invariably proved less satisfactory, 

 and it should be clearly understood that to obtain reliable results 

 the iron-hsematoxylin method, tedious though it be, must be used, 

 although very pretty pictures are often obtained with the Giemsa 

 method. 



Working in this manner, some 300 cases have been syste- 

 matically examined, and the presence of amoebae has been demon- 

 strated in every one. Twenty normal mouths were also examined, 

 and in every case, provided there was no trace of gingivitis, no 

 amcebse could be demonstrated. 



In every case of pyorrhoea examined, the same type of micro- 

 scopic picture was found. Amcebse were present in either large or 

 small numbers, and the number of amcebse found bore no relation 

 to the severity of the disease, neither could the presence or absence 

 of tartar be taken as any criterion as to whether amoebae would be 

 found or not. In many cases examined no traces of tartar forma- 

 tion could be demonstrated, yet amoebae were always to be found, 



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