392 



BACILLI WHICH CAUSE FERMENTATION. 



Morphological 

 haracters. 



Eeaction \vith 

 iodine. 



Other situa- 

 tions in which 

 leptothrix is 

 found. 



Leptothrix 

 gigantea. 



Rasmussen's 

 species of 

 leptothrix. 



It was regarded as characteristic of the latter form that 

 the threads were mixed with dense masses of micro- 

 cocci ; further, according to Leher, the threads of lepto- 

 thrix huccalis show a special reaction : they assume a 

 violet colour under the action of iodine and acids ; 

 iodine alone does not cause this coloration, acids must* 

 be added at the same time ; but it is not necessary to 

 employ sulphuric acid (if it were so the reaction would 

 have a great resemblance to' that of cellulose), very 

 dilute hydrochloric acid, acetic acid, or lactic acid, act 

 even better than sulphuric acid. If the. medium is 

 already acid the addition of iodine alone is sufficient to 



produce the colour. It is 

 not the sheath which 

 stains ; on the contrary 

 it remains colourless, and 

 only the contents become 

 violet; the septa of the 

 threads remain unstained, 

 and hence can be dis- 

 tinctly seen. 



Leptothrix has also been 

 found in the concretions 

 in the tear-ducts, as well as in the sputum in cases of 

 gangrene of the lungs (Traube, -Leyden, and Jaffe) ; 

 and Leber has recently demonstrated that Leptothrix 

 buccalis, when inoculated on the cornea, causes severe 

 suppuration, and that during the course of this process 

 very fine, long, jointed threads and chains of rods are 

 developed, which show the characteristic iodine reaction.* 

 Miller has described a form, under the name of 

 Leptothrix giyantea, which occurs on the teeth of sheep, 

 cattle, and other animals, and which forms very long and 

 thick threads, and may also appear in the form of rods, 

 cocci, and spirilla. 



Rasmussen isolated from the human saliva by the aid 

 of nutrient jelly and potato cultivations a number of 

 bacteria, of which he reckons three as species of lepto- 

 thrix, because they form in nutrient solutions (urine, meat 



* Arch. f. dphthalmol, vol. 15. 



Fig. 112. Leptothrix buccalis 

 X 1000. 



