286 



Profs. Percy Frankland and Marshall Ward. 



investigation. Indeed, some of the first questions I set myself were 

 the following : — (1.) What Schizomycetes are ordinarily found in 

 the water? (2.) Are any of them pathogenic? (3.) Does Bacillus 

 anthracis occur in the Thames ? And (4) how do the aquatic forms 

 behave in cultures ? 



Our preliminary examinations showed that several forms of Schizo- 

 mycetes can be distinguished as common in the water, while here and 

 there a yeast and a mould have been met with. I shall defer the 

 consideration of all the other forms, with the exception of the one 

 treated below. 



Of these several forms we have been strongly impressed with the 

 characters of some, while others have shown such slight individuality 

 that it is difficult to be sure of their autonomy. 



Of the well marked forms, one very common one is particularly 

 characterised by its rapid growth and liquefaction of the gelatine, 

 with a greenish hue and slightly putrid odour. This form is very 

 like one of the forms known as; Bacterium termo, and separated by 

 Mace as Bacillus termo* For some time we thought this was the 

 species referred to, but prolonged and careful isolations and cultures 

 have shown quite clearly that it is the form described by Fliigge 

 under the very descriptive name of Bacillus fluoresceins liquefaciens.f 



It occurs on the gelatine plates at all ordinary temperatures up to 

 20° C, as minute, greyish- white points, which rapidly enlarge to 

 circles, and soon begin to liquefy, so that the colony lies at the base 

 of a perfectly circular concave depression as a granular floccnlent 

 mass with a tinge of green, and with irregular radiations or net- 

 works into the liquefied circular area. 



In from twenty-four to forty-eight hours the area of liquefaction 

 extends very rapidly — in forty-eight hours at 12 — 15° C. the colonies 

 were each as big as a shilling — and soon floods the plate with a 

 slightly malodorous slimy fluid, of a pale emerald- green hue, with 

 a very distinct fluorescent shimmer. 



Such colonies consist of very short fine rods, often with a slight 

 constriction, or in couples, and then difficult to distinguish from 

 chains of cocci, from 2 to 35 jx long by 0"^ to 0'8 fi broad (measured 

 after staining in Spiller's purple and mounting in Canada balsam) ; 

 in no case have we found filaments or spores in the gelatine cultures. 



If transferred to gelatine tubes, the same depression, rapid lique- 

 faction, and green fluorescence are observed at 12°, 15°, and 20° C. ; 

 and if the culture is made as a " stab," a very characteristic series of 

 events follow. The liquefaction of the gelatine proceeds so as to 

 form a funnel, very like a " thistle-head " in shape, and the flocculent 

 greyish-white colonies fall slowly to the bottom of the rapidly 



* Mace, ' Traite pratique de Bacteriologie,' pp. 585 — 587. 

 f Flugge, ' Die Mikroorganismen.' 



