Prof. H. Marshall Ward. 



undoubted resemblances to Loffler's B. diphtherial. It was not found 

 to be pathogenic to guinea-pigs by Dr. Kanthack. 



Group XIX was made to contain a white micrococcus of the type 

 M. candicans of Fliigge. It is very common in the river, and was 

 kept under observation a long time, with interesting results ; for 

 although typically a non-liquefying form, it becomes capable of lique- 

 fying gelatine in time, and the plate-colonies and other cultures show 

 variations which lead me to connect M. candicans with Zimmermann's 

 M. concentricus, Tataroff's " schminkeweisser Streptococcus " and some 

 other forms, as mere varieties of one and the same species. 



Group XX contains a form only isolated once from the Thames, 

 but studied very thoroughly in 1894. It develops lemon-yellow 

 liquefying colonies on gelatine, and presents close resemblances to 

 Sarcina lutea, but it is a fairly large bacillus, and no attempt to 

 convert is into a Sarcina form succeeded. All efforts to match this 

 form among those described have failed, though incompletely 

 examined forms by Maschek, Unna and Tommasoli, and Adametz 

 present resemblances, so far as their imperfect diagnoses go. It 

 may be necessary to name it as a new species. 



Group XXI contains two varieties of a short oval form, or coccus, 

 principally characterised by the development of a red pigment, vary- 

 ing from pale salmon-pink to deep rosy-scarlet, but also differing in 

 details of shape and adaptation to temperature, and a few other 

 points. Nevertheless it was difficult to give the varieties specific 

 rank on the evidence. I have been unable to identify this 

 form. 



Group XXII comprises two forms, not completely investigated, 

 and nearer the type of Group XIV than any others of my groups. 

 Both seem common in the river. 



The question of the pathogenicity or otherwise of these forms 

 was naturally raised, and was kindly tested for me in several cases 

 by Dr. Lazarus Barlow, and at much greater length by Dr. Kanthack, 

 through whose hands nearly all the forms have passed. In the 

 following summary pathogenic means pathogenic to guinea-pigs. 

 Pathogenic varieties occurred in Groups IV, V, VI, VIII, XI, XIII, 

 XIV, and XVII, with considerable variation in detail, while the other 

 groups seem to be harmless. The most markedly pathogenic forms 

 were in Group V (type of B. coli commune). Those in Group IV 

 aroused the suspicion that B. pyocyaneus comes here ; and it is inter- 

 esting to note that B. prodigiosus (Group XIII) was pathogenic in 

 some cases. 



Of course no full test of pathogenicity is afforded by the few 

 trials made in this way, but the positive results obtained at least 

 show that a not inconsiderable number of the river bacteria are 

 pathogenic, or can become so in culture. Not- less important is the 



