[HARRISON] VISCOUS FERMENTATION OF MILK AND BEER 91 



in the sack slowly became acid and finally coagulated but never became 

 slimy. These experiments, therefore, showed that in the varieties studied 

 there were no diffusable slime-producing enzymes. It is true that 

 slime has a very small capacity for diffusing through membranes, and 

 therefore these experiments did not prove that the slime was attached 

 to the bacteria body, as would be the case if it were the product of 

 capsules or of slimy layers round the bacteria. An insight into these 

 conditions was obtained in another way. In cultures of varieties 

 belonging to Groups I and IV, the slimy change was confined to certain 

 regions in which the bacteria grew. There was no solution of the 

 slime mass in the liquid, but a slow, slimy growth which extended down- 

 wards from the surface. The slimy mass remained together like frog 

 spawn. This fact indicated that the slimy mass was more or less bound 

 to the bacterial body. 



All bacteria of Groups I and IV possessed a capsule or a capsule- 

 like envelope. These capsules were formed in milk as well as in other 

 cultures, but were not invariably present. Young cultures possessed 

 capsules as well as old ones, but the best results were obtained with 

 milk cultures 6 to 8 days old. Johne's, Welch's, and Ott's methods 

 of capsule staining were employed with equally good and bad results, 

 sometimes capsules could be usually demonstrated by these methods, 

 and at other times not at all. The capsules of the varieties of Groups 

 III and IV were clear or slightly reddish, when stained with gentian 

 violet, they were a half or as thick as the cell body and were sharply 

 defined. In the varieties of Groups I and II the capsules were from 

 one to three times the width of the cell, clear or slightly red, and sharply 

 outlined. j\Iore often, however, the capsules were irregular, the sharp 

 ouMine was only visible at some places, whilst at others the icapsule 

 contents appeared in irregular and slightly coloured masses which sur- 

 rounded the whole bacillus and capsule. Chains of bacteria were often 

 surroimded by a single unsegmented large capsule. In old cultures cap- 

 sules which contained no bacteria, or only a few well stained granules, 

 or a faintly stained irregular bacillus, were observed. Most frequently, 

 efforts to obtain distinct capsules were failures. Usually the bacteria 

 were surrounded by an homogeneous or slightly granular zone; and this 

 mass must be considered as the result of the swollen and destro3'ed 

 capsules and it had all the qualities of real slime. If preparations were 

 examined without staining, tbe slimy mass could not be seen; but if 

 a little acetic or other acid was added, it at once became visible as a 

 slightly dark, homogeneous granular, or even slightly fibrinous mass 

 attached to the bacteria. The decaying baftorial cells perhaps under- 

 went a slimy degeneration and contributed to tbe slime formation, a. 



