APPENDIX. 417 



spreading into cracks and forming a layer of considerable thickness ; 

 micrococci about i to 1.5/4 in diameter, dividing into four, which remain 

 united by a gelatinous envelope, or there may be a large round cell in 

 which there are found indications of division ; kills white mice, but not 

 ordinary mice ; produces local abscesses or septicaemia in guinea-pigs ; 

 rabbits and dogs are unaffected ; unlike sarcina in dividing in two planes 

 only. 



B. The colonies are yellow. 



a. The colonies form raised drops. 



b. The colonies form flat deposits. 



a. The colonies form raised drops. 



(1) Staphylococcus cereus flavtis. Forms white points in two days ; 

 colonies spread on surface with irregular margins gradually assuming a dark 

 citron yellow colour ; in the early stages the growth is almost like micro- 

 coccus cereus albus ; cocci 1.15/4 in diameter, single, in groups, or in short 

 chains, found in pus ; set up no pathogenic action. 



(2) Micrococcus flavtis tardigmdiis. Grows very slowly (four to six days) ; 

 in gelatine occurs as rounded or oval, dark chrome yellow coloured points ; 

 on the surface these have smooth wax-like surface, and project slightly, 

 especially near the centre ; colour is always darker in the deep layers ; along 

 track of needle in puncture occurs as minute yellow isolated points, which 

 do not make their appearance for six or seven days ; large coccus, sometimes 

 with peculiar dark poles. 



(3) Diplococcus citreus conglomeratus occurs in certain forms of pus and 

 in dust ; on gelatine plates forms citron yellow colonies, raised at the 

 margins, at first moist and slimy, gradually becoming cracked and scaly, 

 forming tuberculated masses which when crushed and diluted with water 

 are seen to be made of cocci resembling gonococcus, or tetrads ; average 

 diameter I-5/*. 



(4) Sarcina lutea grows rapidly on gelatine plates ; appears in two days 

 as yellow points with somewhat irregular and scalloped outlines, yellow in 

 the centre, grey in the intermediate zone and transparent at the periphery ; 

 occurs in air ; made up of rounded cells 1.2/1 in diameter, dividing in three 

 axes, thus giving rise to the well-known corded packets. 



(5) Sarcina aurantiaca (Orange sarcina). Forms small colonies in plate 

 cultures with smooth outlines ; along the track of the needle of a gelatine 

 tube culture it grows very slowly, but best at the ordinary temperature of 

 the room, as a whitish growth ; at the surface it forms an orange yellow 

 layer ; cocci which look as if cut in two, arranged in twos or fours, or in 

 regular packets. 



b. The colonies form flat deposits. 



(i) Micrococcus versicolor grows rapidly, forming white points in twenty- 

 four hours, which twenty-four hours later become yellow ; spherical 

 growths in the gelatine, outline sharp, substance yellowish green in 

 colour, and opaque; on the surface growth is irregular or square; has a 

 peculiar gelatinous consistence, and a yellowish green iridescent shimmer ; 

 although the growth is flat it may be slightly raised in the centre ; along 

 the needle puncture the yellowish colonies are developed separately ; small 

 cocci are arranged in pairs, or in masses. 



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