338 



Appendices to Fifth Annual Report 



jelly with a copious deep red sediment. The breaking up of the surface 

 film and the subsidence of the particles thereof give rise to a more or less 

 granular opalescence in the liquid gelatine, which after a time disappears, 

 leaving the jelly quite clear in some cases, but in others of a rosy pink. 

 The liquefaction is so slow, that several weeks may elapse before any sign 

 of its occurrence. In one tube which was carefully watched, no liquefaction 

 Avas perceptible till the end of three months, and was not complete at the 

 end of six months. 



Microscopically. — Same as from Plate Cultivation. 



Bread Paste. — Grows at first as a pinkish spot at point of inoculation, 

 which rapidly increases in size and develops its characteristic magenta 

 appearance. In some flasks, after it had made a certain advance around 

 point of inoculation, the growth made its appearance at the margin of the 

 flask, and extending inwards became fused into that growing from the 

 centre. The peculiar greenish iridescence is well seen in some cases" after 

 a short time, in others it is not so well developed. In a somewhat moist 

 soil, and at an average summer temperature, the growth of this micro- 

 coccus is very rapid, and closely resembles that of the Micrococcus pro- 

 digiosus. from which it differs in that it does not cause rapid liquefaction 

 of the jelly, and that it develops the peculiar greenish iridescence above 

 described. 



After a time a dirty greyish white coating .appears over some parts of ' 

 the growth. 



The bright magenta hue becomes darker, and assumes a brownish-red 

 in most of the flasks after the lapse of some weeks. 



Microscopically. — The micrococci appear larger than those taken from 

 jelly — some even 1*27 fx in diameter. 



Examined unstained, some of these micrococci appear to contain the red 

 pigment in their substance, as they are found bright red under a power of 

 700 diameters. They seem, however, to hold the colouring matter very 

 loosely. When examined in distilled water, only a very few appear red, 

 the colouring matter being found in small masses scattered here and there 

 throughout the field, these masses having no definite size or shape, and 

 quite free and distinct from the micrococci. If, however, a thin film of 

 the organisms be carefully dried on a coverglass, and mounted unstained 

 in benzol balsam, many of them stand out bright red under the microscope, 

 and these may retain their distinctive colour for a considerable time, pro- 

 bably months, ultimately yielding it up to the surrounding balsam. The 

 older more fully developed micrococci retain the colouring matter longer 

 than those less mature. 



Chemical Reactions. — The pigment requires for its production the 

 presence of air, as it is not developed in connection with those organisms 

 which are situated in the deeper parts of gelatine cultures. It is readily 

 soluble in distilled water, slightly so in absolute alcohol and glycerine. 

 Strong nitric acid causes an immediate disappearance of the red colour. 

 Strong hydrochloric acid turns it first dark violet, and afterwards of a 

 pale violet colour. Strong ammonia, and a solution composed of 1 grm. 

 fused caustic potash in 100 c.c. absolute alcohol, change the pigment to a 

 brown, then a yellow, finally making it almost entirely disappear. Strong 

 sulphuric acid, turpentine, benzol, and oil of cloves appear to have no 

 effect on it. Chloroform changes it to a pale pink. 



Comparison with Micrococcus prodigiosus. — Striking differences exist 

 between the magenta micrococcus and the Micrococcus prodigiosus, which 

 may be briefly summarised. Micrococcus prodigiosus liquefies peptonised 

 beef gelatine pretty rapidly, Magenta micrococcus does not unless very 

 slowly. Cultivations kept three months at a summer temperature may show 



