BEGGIATOA 509 



DIPLOCOCCUS LUTEUS 



LIQUEFIES GELATINE 



Authority. Adametz, Die Bakterien der Nutz- und Trinkwasser, Vienna, 

 1888. 



Where Found. In water. 



Microscopic Appearance. Cocci about 1-2 to 1-3 /* in diameter. It occurs 

 mostly as diplococci, but forms also small groups and also chains of ten indi- 

 viduals. It is very motile ; the chains have a worm-like movement. 



Cultures. 



GELATINE PLATES. In three days circular, bright-yellow colonies of a tough, 

 slimy consistency are visible. Under a low power the centre is yellowish 

 brown ; towards the rim, which is smooth, the colour is bright yellow. In six 

 days the colony is 8 mm. in diameter, and is of an intensely yellow colour. 



GELATINE TUBES. Forms an abundant growth on the surface. The growth 

 is circular, lemon-yellow in colour, and exhibits concentric circles. In about 

 ten days an intensely brownish red colour appears in the gelatine beneath the 

 surface growth, and seems to pervade it like a cloud, becoming less intense 

 lower down. The gelatine is softened, and after some weeks liquefaction com- 

 mences. 



AGAK-AGAR. Produces a tough, slimy, yellow growth on the surface, whilst 

 in the depth the agar becomes of a brownish red tint. 



POTATOES. Forms a dirty yellow expansion, which later becomes brownish 

 and emits an odour characteristic of moulds. 



MILK. In five days the milk is coagulated. 



Remarks. Does not ferment sugar solutions. 



BEGGIATOA 



The individuals belonging to this group are distinguished from those pre- 

 viously described by one extremity being usually attached to some point of 

 support, whilst the other remains free. Moreover, their protoplasm contains 

 very frequently sulphur granules which are not crystalline. The Beggiatoa 

 represent a type of algae which are much more highly organised than the bac- 

 teria, and approach the group known as Oscillatoriae, but differ from the latter 

 in having no phycocyanine or chlorophyll. Beggiatoae are nearly invariably 

 present in thermal sulphur waters, and are also constantly found in polluted 

 and stagnant waters. They are divided into two principal classes, Beggiatoa 

 and Crenothrix, whilst Winogradsky has added the sub-class Thiothrix. 

 Winogradsky has made a special study of the forms of Beggiatoa in sulphur 

 waters, and has found as many as fifteen genera and more than twenty-five 

 different species. This author is of opinion that the sulphur granules are due 

 to the oxidation of the sulphuretted hydrogen in the water, and that this sul- 

 phur is converted into sulphuric acid by the plant (Annales de VInstitut 

 Pasteur, vol. iii., 1889, p. 49.) 



BEGGIATOA ALBA (Vaucher) 



"Where Found. It is very widely distributed in sewage and in drain-water 

 from sugar factories, in thermal-sulphur springs, &c. The threads are found 

 attached to dead insects or decayed plants, and produce white mucous flakes, 

 which grow to considerable dimensions. 



Microscopic Appearance. The threads are from 1 to 5 /* thick, and from 

 3 to 4 ft long ; they are bent in the shape of sinuous arcs or spirals. The free 

 extremity is rounded, and the thread, more especially towards this extremity, 

 contains large sulphur granules. The filament is articulated. It will grow 

 luxuriantly at 55 C. 



