of the Fishery Board for Scotland. 



339 



no trace of liquefaction. This also serves to distinguish it from Bacillus 

 indicus. The iridescence of the Magenta micrococcus is also never observed 

 on Micrococcus prodigiosus. 



Microscopically, when studied side b.y side, the difference is very 

 striking. Micrococcus prodigiosus is much more uniform in size, more 

 spherical, and frequently forms chains of 3 or 4. Its diameter is, on an 

 average, smaller, about *48 /x, whilst Magenta micrococcus is '4 to *6 /x. 

 In Magenta micrococcus chains were never seen, the cells more oblong or 

 ovoid; Diplococci frequent, often giving the appearance of short rods, 1 /x to 

 IT long. 



Other differences, e.g. y in the colour spectrum, need not here be 

 described. 



2. White Micrococcus. From Tweed — Melrose — right bank above 

 the < Cauld.' 



Plate Cultivation. — In summer the growths appear on the second day 

 as minute grey specks. On the third day they are seen as rounded points 

 varying in size, and under a low power have the usual globular form with 

 well-defined margin, and dark granular contents. There is no liquefaction 

 of the gelatine. 



Test Tubes. — Growth commences as a small greyish-white spot on the 

 surface around the point of inoculation of jelly. It slowly enlarges, 

 assuming a more or less circular form with somewhat elevated margin and. 

 slightly depressed centre. Along the needle-track little or no evidence of 

 growth is seen. In its further progress the growth causes a deep cup- 

 shaped depression of the gelatine, which increases with the increase of the 

 growth, and is lined by a thin film. No liquefaction of gelatine occurs. 



Bread Paste. — This growth is almost indistinguishable on bread paste. 

 It grows very slowly as an apparently colourless or slightly greyish film 

 on the surface, and becomes somewhat darker after a time, so as to appear 

 of a faint grey or greyish-yellow. 



Microscopically. — Bound or slightly ovoid micrococci, having a diameter 

 of about *89 to 1T5 fx. Some of the dividing cells (Diplococci) have a 

 diameter of *8 /x broad by 2 /x long. 



3. Violet Bacillus. — Tweed — Melrose. 



This appears to be identical with the Bacillus violaceus or Bacterium 

 Ianthinum, which is now well known to bacteriologists. In every 

 respect it appears to conform to that organism. It is not at all uncommon 

 in river water, if w r e may judge from the frequency of the occurrence of 

 its colour in flask cultivations. 



Plate Cultivation. — On the third day numerous grey round colonies of 

 growth are seen. Most of these have caused liquefaction of the surround- 

 ing jelly. Under a low power the points consist of the usual globular 

 form, with a zone of liquefaction around them. The violet colour is not 

 developed on the plate cultivation, the growth as well as the liquid jelly 

 remaining grey in appearance. 



Test Ttd)e Cultivation. — On the second day a funnel-shaped bag of lique- 

 faction occupies the place of the needle-track, the apex being directed down- 

 wards. The liquid gelatine is opalescent, and a greyish sediment fills up 

 the apical portion. Extension of liquefaction takes place more rapidly at 

 the surface, and in a few days a layer of liquid gelatine may be seen on 

 the top, and a funnel-shaped sediment beneath, which now is distinctly 

 violet in colour. Liquefaction may take place from above downwards, 



