140 AMEB^ 



belief of a number of investigators that the common ameba of 

 the mouth, Endamoeba gingivalis (buccalis), has a pathogenic 

 effect, and is the cause of pyorrhea. Although amebae have not 

 yet proved to be the direct cause of any diseased condition of 

 the mouth, yet this direct relation has been shown recently to be 

 by no means impossible, and an indirect relation is very probable. 



Pyorrhea, or Rigg's disease, in some stage afHicts the majority 

 of all adult people, and over 50 per cent of all permanent teeth 

 which are lost are lost as the result of pyorrhea. The apparent 

 relation between this disease and the presence in the mouth of 

 the above-mentioned ameba, E. gingivalis (buccalis), was first 

 demonstrated in 1914 by Barrett, and since then the relation- 

 ship between the disease and the amebse has been so well estab- 

 lished that there can be little doubt of it, except as to whether the 

 amebse cause the disease directly by destroying the tissues or in- 

 directly by injuring the tissues and facilitating the entrance of 

 bacteria. The prevalence of amebse in the mouth, even in young 

 children, is well shown by a recent investigation by Anna Wil- 

 liams of the mouths of over 1600 school children in New York 

 City. Of the children between five and seven years of age 35 

 per cent were found infected, while of those between five and 15 

 years 60 per cent were infected. 



The ameba, E. gingivalis, which does the damage can be 

 " shown up " by placing a bit of the pus from a tooth pocket on 

 a microscope slide. Here the villains will be found in the midst 

 of their wreckage. They are from one to three times the diameter 

 of the pus cells, usually from 12 to 20 n (^^yViy to TTirw of an inch) 

 in diameter, and have a granular appearance; the nucleus is rela- 

 tively very small. Often when stained they show dark bodies 

 inside of them which are probably the nuclei of other organisms 

 or of semi-digested pus cells. When living the amebse prowl about 

 sluggishly, pushing out a blunt pseudopodium now on one side 

 of the body, now on the other, then drawing up the body, and 

 pushing out more pseudopodia, thus slowly working their way 

 about between the pus cells and fragments of tissue. The outer 

 layer of the body, or ectoplasm, which serves as a sort of protect- 

 ing envelope, like the rind on a melon, is clear and transparent 

 but is not readily distinguishable except when the animal is 

 moving. The pseudopodia are always formed first out of this 

 clear ectoplasm, the more granular, grayish inner substance or 



