196 Transactions of the Society. 



lysing action could be observed at any time. A remarkable fact 

 that has recently been brought to light by this research is, that 

 in a large number of pyorrhoea cases examination of concen- 

 trates of the fseces, prepared by the method described by Penfold, 

 Woodcock, and Drew {5), has shown cysts to be present which 

 bear a very striking resemblance to those described by Elmassian 

 as Entamceha minuta, and we have found it quite impossible, up to 

 the present, to cultivate such cysts. This point would appear to 

 be of importance, as mistakes in dysentery diagnosis miglit occur 

 by confounding such cysts with those of the pathogenic dysentery 

 amoebse.. The cysts observed in these pyorrhoea cases measured 

 from 7-8 /j, in diam., and when examined in the free state no 

 definite nucleus could be observed. When, however, Gram's iodine 

 solution was mixed with the faeces, the cysts were found to show 

 two ring-shaped nuclei. We would suggest that these cysts 

 probably represent those of U. gingivalis, and we are inclined to 

 think that many of the so-called minuta infections are really of 

 this nature. 



Having obtained cysts in large quantities, we determined to see 

 whether advanced cases of pyorrhoea showed any complement fixa- 

 tion, using as antigen both alcoholic and saline extracts of the 

 cysts. Blood from twelve cases was taken and treated, but in 

 only one case was there the slightest evidence of any fixation of 

 complement. 



It is not our intention to deal with the purely clinical side of 

 pyorrhoea in the present paper, but so far as we have gone in this 

 research the conclusions regarding the causal role of the amcebse 

 in pyorrhcea are that they have little to do with the disease. 

 Mechanical injury seems to play an exceedingly important part in 

 the commencement, which in our experience appears to start almost 

 invariably as a marginal gingivitis. Spirochsetes and trepone- 

 mata are well known to possess the power of boring into the 

 tissues, and many of them, such as the Spiroch/vta, vinccvti, may 

 cause much tissue destruction, which is well seen in certain 

 cases of Vincent's angina. We think that when once injury has 

 occurred the spirochsetes play the chief part in the disease, causing 

 the tissue destruction and formation of pockets. When once 

 pockets have been formed, the pyogenic cocci and other organisms 

 find an exceedingly good breeding ground, where toxin formation 

 and absorption can go on continuously ; and, in considering the 

 treatment of the disease, we think this secondary bacterial infection 

 should always be borne in mind. The amoebse, however, when 

 once established in the pockets would certainly appear to aid the 

 destruction of tissue, and it seems certain that they cause a good 

 deal of destruction amongst the red cells. Lately we have found 

 the use of arsenic preparations, such as atoxyl and salvarsan, of 

 great value, but we think that in all cases vaccine treatment in 



