426 APPENDIX. 



(3) Bacillus pseudopneumonicus. Very like the true bacillus of pneu- 

 monia ; but it has been found in pus taken from abscesses. The colonies 

 seen through the microscope are dark grey in colour, and finely granular ; 

 puncture cultures in gelatine have the characteristic nail appearance ; 

 grows rapidly, and differs from the two previous forms in that it causes 

 rather dark coloration of the gelatine, and gives rise to a slight putrefactive 

 odour ; grows well on potatoes as a white, viscid layer, but no gas is formed 

 even at a temperature of 37 C. Requires air for its growth ; micro- 

 scopically it is very like the pneumonia bacillus, i.i6/* in length, and .gp. 

 in diameter. It is only slightly, if at all, pathogenic. 



/3. Colonies with smooth borders. 



(1) Bacillus oxytocus perniciosus. Obtained from milk that had been 

 allowed to stand for a considerable time. Occurs on plate cultures as 

 small colonies, with smooth borders and circular outlines ; under the micro- 

 scope appears to have a light brown colour ; growing on the surface may 

 attain a size of 1.5 mm. ; colonies are greyish white, and are usually round ; 

 needle cultures have, at first, the characteristic nail appearance but, 

 after a time, the growth along the needle track is comparatively small, 

 whilst the surface growth becomes very extensive ; gives a peculiar acid 

 reaction to milk but no odour is developed ; under the microscope it 

 is seen as a short rod with rounded ends, somewhat thicker and shorter 

 than the lactic acid bacillus. In large doses is fatal to rabbits. 



(2) Bacterium lactis aerogenes. Found in the small intestine of mam- 

 mals and sometimes even in milk. Colonies have smooth borders ; 

 do not spread out much, but are usually of considerable thickness, like 

 little white porcelain points. In needle cultures it grows luxuriantly in 

 the nail form ; along the line of the needle, small rounded points occur at 

 regular intervals, so that the growth looks almost like a string of beads ; 

 forms white layers on potato, in which bubbles of gas are frequently 

 developed, sometimes this layer has a peculiar creamy appearance ; grows 

 rapidly at about 37 C. ; causes diarrhoea and collapse in rabbits and guinea- 

 pigs, but does not affect mice; short thick rods with rounded ends I to 2\i 

 long and .5 to .8/1 broad ; usually occurs in pairs, or may be arranged in 

 irregular masses ; the organism is non-motile. 



(3) Weisser bacillus. Obtained from water. Grows on gelatine plates 

 as round smooth white pin-head-like colonies ; in gelatine tubes it grows 

 slowly, forms a whitish mass along the track of the needle and a white 

 head on the surface ; on potatoes it forms a yellowish-white growth ; grows 

 slowly ; the organism is a short motile bacillus with truncated ends, 

 often joined to form chains. 



d. Colonies are branched, not circumscribed. 



(1) Bacterium Zopfiii. First found in the intestine of fowls. It grows 

 on plates almost like a mucor ; in needle cultures appears as a thick, pale, 

 yellow string, from which white branches radiate into the surrounding 

 gelatine ; is strongly aerobic, and grows very rapidly, especially at a 

 temperature of about 20 C. ; spores are formed which are extremely 

 resistant to heat ; the organism is from 2 to 5j in length and from .7 to i/i 

 in breadth ; is motile ; occurs in long threads, which in gelatine show 

 numerous bends or spirals. 



(2) Bacillus of Mouse Septiccemia* Originally found in garden earth and 



