204 THE ROYAL SOCIETY OF CANADA 



both divide and at once form a cluster of four. When one side of a 

 cluster grows more quickly than the other an irregular rosette develops. 



After a cell forms a dividing wall it does not always swing apart, 

 but may remain attached, thus lengthening, as it were, the individual 

 rays of the cluster. 



All these phases of growth may be observed in the accompanying 

 microphotographs, which should be examined with a magnifying 

 glass. The clear space in the centre of the rosette, comparable to the 

 eye of the daisy or aster, varies in size, the larger the cluster the larger 

 is the central clear area. 



Free organisms swimming in the hanging drop will often become 

 attached to a cluster and grow with it, although as often they will move 

 away. 



In milk and whey rosettes develop freely, on whey gelatine they 

 are less numerous. 



Staining. The organism stains fairly well with the ordinary 

 stains, but accepts the colour better after immersion in weak acetic 

 acid. It is Gram positive. 



Appearance of the Organism and Occurrence of Rosettes in Various 

 Media. The bacilli are motile, but in the rosette stage the motility 

 is lost, except at. times a slight swaying motion of the free ends. 

 The organism is peritrichous. The flagella stained by Van Ermegem's 

 methods vary in number, usually from five to seven. 



On unhopped wort, whey, yeast water and beef peptone gelatine 

 rosette formation occurs. Single organisms in liquid cultures of 

 sweet wort are of peculiar shapes, lemon and crescent shaped forms 

 are common, and the individual elements of the rosettes are often 

 slightly club shaped. In hopped wort the rosettes are smaller. 



In yeast water, milk, and the usual sugar media rosette formation 

 occurs freely. After two or three days' growth the organisms com- 

 posing the clump become more uneven or club-shaped. 



Cultures. On beef peptone and whey gelatine the colonies are 

 punctiform. Surface colonies are slightly larger, averaging about 

 1 -5 mm. in diameter, and cause a very slight depression in the gelatine 

 which, however, cannot be definitely ascribed to liquefaction. When 

 grown with the viscous milk organism the gelatine is liquefied, a 

 result which neither organism can accomplish when growing separately. 



The deep colonies are very regular, the edge sharply defined when 

 examined with low power objective. The surface colony is not so 



