Oyi Certain Parasites of the Mouth in Cases of Pi/orrhcea. 521 



cause of the disease owing to the following erroneous assump- 

 tions : — 



1. That they burrow down into the tissues destroying the 

 peridontal layer and being found in greatest quantities in the 

 deeper parts of the pockets. [It has already been mentioned that no 

 signs of them can be found in the peridontal layer, and they only 

 go below the gum when carried there by the sheltering tartar.] 



2. That they are not found in healthy gums. [This statement 

 has been contradicted by their own country-woman, A. Williams, 

 and her collaborators (14), who record that they found amcebfe in 

 2 'J p.c. of New York children with healthy gums. Lewald (.9) in 

 1907 had even recorded them in a much higher percentage of what 

 he called healthy mouths.] 



3. That emetin, which has such extraordinary amoebicidal 

 action on U. histolytica, causes the amoebse to disappear from the 

 gums, and is followed by an improvement in their condition. 

 [This they admit themselves in a subsequent note (1, p. 143) not 

 to be invariably true, and in none of the few cases that we have 

 kept under observation during injection of emetin (J-1 gr. a day 

 for six days) have the amoeba? disappeared for any length of time. 

 In fact not at all generally, and in one their disappearance for 

 a few days we ascribe to the unaccustomed oral cleanliness, kept 

 up under our supervision, as much as to the effect of the drug.] 



Another argument against E. gingivalis being a potent cause 

 of pyorrhoea is the fact that in advanced cases there are sometimes 

 very few — many less than in other milder ones. In fine, the short 

 notoriety, that the amoeba had for about a year as the cause of 

 pyorrhcea, has practically already died down. 



Another Protozoan parasite sometimes present in pyorrhoea 

 lesions is Trichomonas. This is presumably the same species, 

 T. hominis, found in the human intestine, where, if in large 

 numbers, it appears to give rise to a mild form of dysentery. In 

 the mouth it is generally only present in small numbers, and we 

 have not so far studied it specially. It lives, as would be 

 expected, for a much longer time outside the mouth than the 

 amcebfe. There is no evidence at all in support of its having any 

 particular connexion with pyorrhoea. 



Desckiption of the Leptothkix of the Mouth. 



The white deposit to be found attached to and between the 

 teeth is chiefly composed of colonies of Leptothrix, which we 

 believe to be a pleomorphic organism. In examining the colonies 

 great care should be taken to obtain them from the mouth in 

 as unbroken a condition as possible. They have a high degree of 

 tenacity, but if the material, scraped, say, from the tartar ridge, 

 be teazed out with needles or made into a smear as in making 



