T. (jtOODey and a. W. Weldings 
545 
finds organisms in which both bacteria and the larger bodies occur 
together, as shown in PL XX, fig. 4. The round bodies present a greenish 
appearance in the live amoebae, and when stained appear to be almost 
homogeneous in structure. They frequently show a narrow clear zone 
around them, separating them from the inner limit of the vacuole, but 
as often seem to occupy the whole area of the vacuole. 
With iron-haematoxylin, the majority of them stain an intense 
black whilst others exhibit various degrees of blackness, and some are 
only faintly stained. 
The black coloration with iron-haematoxylin suggests that they are 
composed of a chromatinic substance, a fact which is confirmed by the 
use of other stains. Safranin stains the bodies bright red, Unna’s 
polychrome methylene-blue stains them deep blue, methyl-green colours 
them green, whilst with Giemsa’s stain they are tinted a bluish purple 
or purple, and Jenner’s methylene-blue eosin stains them blue or 
greenish blue. 
All these stains, therefore, show that the bodies are rich in chro¬ 
matin, and that they are probably derived from nuclear material. They 
also definitely rule red blood cells out of the question. 
This is important, for it shows that the bodies are not of the same 
nature as the ingesta of E. tetragena, in which red blood corpuscles are 
frequently found. 
Nor are whole polymorphonuclear leucocytes ever to be found within 
the amoebae, although endothelial cells showing ingested polymorpho¬ 
nuclear leucocytes are frequently observed in material from pyorrhoea- 
pockets or from inflamed areas of the gums (PI. XX, fig. 8). 
In size the bodies vary from about 1 /a to 4 or 5 p, in diameter, our 
measurements agreeing with those given by Craig. 
Having satisfied ourselves of the chromatinic nature of the deeply 
staining bodies we set out to discover their origin. It was evident that 
they were of common occurrence in the mouth, and were not confined 
to pyorrhoea pockets although they were to be found in amoebae from 
these situations as well as from any other part of the gums or necks of 
teeth. We were not satisfied that they were derived from polymorpho¬ 
nuclear leucocytes, for none of these ever showed nuclei of the homo¬ 
geneous type and having the same staining reactions as the round bodies. 
We were, therefore, driven to make as thorough a search as possible for 
the source of the round bodies. 
Careful examination of our films carrying amoebae showed that, 
scattered about amongst the innumerable bacteria and leucocytes. 
