BEGQIATOA ALBA. 461 



Regarding the forms designated as " Leptothrix buc- 

 calis," which occur frequently in the mouth, especially 

 in deposits on the teeth, little can be said that is satisfac- 

 tory, since cultures have almost always failed. 



Miller (Die Bakterien der Mundhohle, II. Aufl., Berlin, 1894) ap- 

 pears to have cultivated no leptothrix. He cites the following uncul- 

 tivated leprothrices, briefly and very insufficiently characterized: 



Leptothrix gigantea Miller. Threads fixed at one end, small to 

 very thick, with or without distinct septa. lodin reaction ? 



Leptothrix maxima buccalis Sliller. Jointed threads 1 to 1.3 ,« 

 thick, without iodin reaction. 



Bacillus maximus buccalis Miller. Like the preceding, but with 

 iodin reaction. It is not stated why this species is designated bacillus 

 while the former are designated leptothrix. 



Leptothrix innominata Miller is said to present slender, 0.5 to 0.8 

 jj. thick, tangled, unsegmented, often wavy or bent threads, which 

 sometimes stain violet with iodin. 



Aiustamow (C. B. VI, 349) described two unnamed leptothrices of 

 the mouth, cultivated by him, both of which grow at incubator tem- 

 perature. No. 1 being an exquisite anaerobe. No, 2 an outspoken 

 aerobe. The agar growth corresponds in some measure to that of the 

 L. epidermidis; potato and gelatin growths are not described. 



Dobrzyniecki (C. B. xxi, 225) has described in detail a Leptothrix 

 placoides alba, which was successfully cultivated aerobically on gela- 

 tin. The growth at first resembled anthrax, and then liquefied. The 

 growth on agar was slow — hard, dense colonies being formed. The 

 organism presents long, jointed threads, with a tendency to form tan- 

 gles, and it stains blue with iodin and iodid of potassium solution and 

 a little lactic acid. Stains by Gram's method. Is not motile. 



Flexner has isolated an interesting organism from a rabbit which 

 died of puerperal infection. It occurs in long threads, is always free 

 of spores, has no motion, and does not branch. It is pathogenic, but 

 very difficult to cultivate outside of the body. He names it Bacillus 

 (Leptothrix?) pyogenes filiformis Flexner (Jour, of Exp. Med., 

 Vol. I, 211, 1896). 



Beggiatoa alba. Vauch. 



Long and rather thick (1 to S/i) unbranched threads, 

 without membranes, and quiet or with a gliding motion. 

 When fresh, there are in part no partitions, but often 

 numerous very highly refracting bodies may be recognized. 

 The granules consist of sulphur, which may especially be 

 recognized if the threads are previously allowed to dry, 

 and also by their solubility in H^S. In this way also the 

 previously indistinguishable transverse partitions become 

 apparent. According to Winogradsky, the breaking up of 



