On Certain Parasites of the Mouth in Gases of Pyorrhoea. 527 



possibly necessary for its growtli, we intend to attempt the cultiva- 

 tion of complete colonies of Leptotbrix ; tins we recognize to be the 

 only conclusive proof that the fusiform, coccoid, and filamentous 

 forms are all parts of the same orujanism. 



We may sum up by stating that pyorrhosa lesions differ from 

 other suppurating sores in that no organisms appear to invade 

 the tissues. Possibly they are kept out by the normal flow of 

 leucocytes being so greatly increased as soon as the epithelium is 

 injured. In any case we cannot yet definitely accuse any organism 

 of being the primary cause of the gingivitis with which we feel sure 

 the disease begins, but are inclined to incriminate the Leptothrix. 



In conclusion, we should like to express our great indebtedness 

 to the authorities of the Eadcliff'e Infirmary, Oxford, especially 

 Major Gibson, D.M., for the use of a laboratory in that institu- 

 tion ; also to the dental surgeons who hold clinics at the Infirmary 

 and have provided us with much material. Mr. Kendrew and 

 Mr. Pettey liave especially given us assistance. Mr. E. S. Goodrich 

 has given lis much valuable advice and help during the progress of 

 the work; and we are also much indebted to Sir William Osier, 

 not only for suggesting the study of this disease, but for the great 

 help he has given us throughout the course of the research. 



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