APPENDIX. 419 



gelatine becomes liquid the border becomes wavy ; along the track of a 

 needle in puncture cultivations there is first a continuous growth, liquefac- 

 tion takes place along this tracli commencing at the surface, and in the 

 later stages the gelatine is liquefied to the depth of the needle track, a 

 sediment of light yellow deposit being thrown down, the liquefied gelatine is 

 somewhat turbid but uncoloured; organism rounded 1.25 to 2/j in diameter, 

 occurs singly or in short chains ; this organism is supposed to convert urea 

 into carbonate of ammonia by a kind of fermentation. 



(3) Sarcina alba. — An organism obtained from the air. Grows slowly on 

 plates as small white colonies along the needle track ; in gelatine grows 

 slowly and forms a white projecting head on the surface of the gelatine, 

 causing very slight liquefaction near the surface ; on agar it forms a whitish 

 yellow layer, which surrounds the point of inoculation ; grows like a small 

 coccus arranged in twos, fours, or packets. 



B. The colonies are yellow. 



a. Gelatine liquefies slowly and imperfectly. 



b. Gelatine becomes completely liquid. 



a. Gelatine liquefies slowly and imperfectly. 



(i) Micrococcus flavus desidens occurs in the dust of the atmosphere; 

 organism grows slowly in the depth of gelatine where the colony has somewhat 

 irregular outline, grows more rapidly at the surface ; it is then dull yellow or 

 brown in colour, is smooth and almost slimy in consistence ; gelatine under- 

 neath is softened, and there is slow sinking of the surface growth, the soft 

 jelly becomes opaque ; the organism is a small coccus ; may be arranged in 

 diplococci, in triangles or in short chains ; is non-pathogenic. 



(2) Micrococcus arogenes (Miller). — Found in the intestinal tract. On 

 gelatine plates forms dark coloured round scalloped colonies with smooth 

 outlines ; under the microscope these may be either opaque or transparent ; 

 in gelatine tubes the growth occurs along the track of the needle as a 

 brownish yellow mass, forming on the surface a flat greyish white porridge- 

 like layer of some thickness ; liquefaction takes place at a later stage ; the 

 same yellowish white porridge-like layer is seen on both agar-agar and 

 potato growths ; it is a large non-motile oval coccus. 



b. Gelatine becomes completely liquefied. 

 a. Colonies remain limited to the centre of the liquefying area. 

 j3. Colonies are found occupying both in the centre and the periphery 



of the liquefying area, see p. 420. 

 a. Colonies remain limited to the centre of the liquefying area. 



(l) Staphylococcus pyogenes aureus (Probably identical with Micro- 

 coccus of Osteomyelitis). — Grows rapidly in plate cultivations ; seen under 

 microscope as light brown circular masses, darker in the centre and with 

 smooth borders ; these become yellow and liquefy the gelatine on the second 

 or third day, forming a little clear cut funnel with an orange yellow mass at 

 the bottom ; liquefying areas gradually run together ; along puncture track of 

 needle in gelatine tube a white mass is formed, which only becomes yellow 

 on the access of air, liquefaction commencing at the surface and extending 

 the whole length of track ; micrococcus .8 to .9/11 in diameter ; occurs in 

 irregular masses, diplococci, tetrads or short chains ; is fatal in large doses 

 tp mice, guinea-pigs and rabbits if injected into the veins or into the 

 peritoneal cavity ; inoculated subcutaneously usually gives rise to abscesses 



