190 Transactions of the Society. 



nected to, what we take to be, a rudimentary undulating membrane. 

 Its motion is extremely rapid, and it executes man}'" darts and 

 twists, occasionally spinning- round with intense rapidity like a 

 top. We have observed all stages of transverse division in this 

 form, which takes place as follows : — 



A. Division of the flagellum takes place at the end attached to 

 the body, and gradually spreads to the distal end. The two 

 flagella now travel to opposite poles, and apparently some sort of 

 division of the chromatin also occurs, as two polar caps of 

 chromatin can be observed at this stage. 



B. Division of the body of the flagellate next takes place by 

 transverse fission, and the two forms go free. On account of the 

 single laterally placed flagellum, the mode of division, and the 

 movements in general, we consider this form to belong to the 

 group of flagellates rather than to the bacteria. It is not intended 

 to devote more space in the present paper to the spirochsetes, as 

 the work is still being proceeded with, and it is our intention to 

 publish a separate paper dealing more fully with these organisms 

 at a somewhat later date. 



Bacteria are invariably present in pyorrhoea, often in immense 

 numbers. 



Streptococci are found in every case. Fusiform bacilli and 

 vibrios are often extremely numerous. Many cocci are present, 

 including such forms as Micrococcus catarrhalis, Staphylococcus 

 albus and S. aureus and M. tetragenus, and others which have not 

 been identified. In the paraffined preparations already alluded 

 to, spirochsetes remain actively motile for two or three days. Eed 

 corpuscles and leucocytes occur in varying numbers ; and in early 

 cases, and in cases showing no macroscopic evidence of pyorrhoea 

 beyond a marginal gingivitis, the presence of microscopic pus was 

 invariably found. In nearly every case immense numbers of 

 leptothrix filaments are present. 



Amceb^. 



The invariable presence of amoebse has already been noted, 

 and these appear to belong to at least two distinct species. The 

 largest form met with measures from 10 /x to 30 yu. in diameter. It 



EXPLANATION OF PLATE XV. 



Fig. 1. — Various forms resembling Trypanosomes (Congo-red film). (The arrange- 

 ment is arbitrary, representing what was thought to be the probable 

 sequence in development.) 

 ,, 2. — The new species of Flagellate, showing the usual method of reproduction. 

 (Congo-red film.) 



