488 



On the Nature of the Fur on the Tongue. [Apr. 24, 



change in appearance for many hours, sometimes for two or more 

 days, after which they usually became granular and degenerated. 

 These bodies are apparently identical with the Leptothrix buccalis of 

 Robin. But I think they would be more rightly called Bacillus 

 subtilis. Their length, their slender form, the conditions in which 

 they occur, and the fact of their non- development in the presence of 

 other fungi point to this conclusion. I made many attempts to 

 separate them in order to produce the fungus in a purer form by 

 cultivation, but did not succeed in doing so. Although this fungus 

 did not develop under artificial conditions in the presence of 

 Micrococcus and other fungi it is highly, probable that its development 

 takes place freely upon the surface of the tongue. Its habitual 

 presence there, generally in tolerable abundance, and the occurrence 

 of spore-bearing filaments may be adduced as evidence in favour of 

 this view. 



Besides these fungi Bacterium termo existed in some of the furs 

 examined, and twice developed with such rapidity that the whole of 

 the fluid was crowded with these organisms to the exclusion of every 

 other form. Pairs, chains, and colonies were formed. 



Sarcina ventriculi was frequently present and generally developed 

 quickly. It usually occurred in pairs or fours, and was easily 

 recognisable by its large size, compared with the other organisms 

 present, by the square or oblong form of its nuclei, by their faint 

 yellow or red tint, and by the area of protoplasm surrounding the 

 nuclei. The groups of two or four moved slowly about the field of 

 the microscope, but the large masses which were formed remained 

 quite motionless. The masses attained so large a size as seriously to 

 interfere with the growth of some of the other organisms, and when 

 large showed a decided yellow, or brownish-yellow colour. 



In two or three of the specimens there occurred rapid and very 

 abundant development of a form of Spirillum, which appeared from 

 the double twist which it exhibited, and from its extreme tenuity, to 

 be Spirochoeta plicatilis. Its growth took place from exceedingly 

 small portions of the organism, and continued only at one end, which 

 was in constant motion, whilst the other end remained stationary ; 

 and as the growth progressed, large masses were formed which soon 

 became so dense that it was impossible to discern the nature of the 

 organism of which they were composed. This Spirochoeta did not 

 occur in most of the specimens examined. 



A larger form of Spirillum w r as also occasionally present, but was 

 not seen in the act of developing. 



Although I believe the fur consists chiefly of Micrococcus and Bacillus 

 subtilis, I think it is probable from the results obtained in the experi- 

 ments upon which the foregoing observations are founded, that the 

 development of these other forms (Bacterium termo, Sarcina ventri- 



