92 Lectures on Bacteria. [§ ix. 



other filaments. Growth is also accompanied with separation 

 of the originally elongated gelatinous filaments into shorter 

 transverse sections, which are always surrounded by the sheath 

 and remain firmly attached to one another (i). Closely twisted 

 coils are thus produced of the size of or larger than a hazel-nut 

 (a), forming the compact gelatinous bodies mentioned above 

 which accumulate and fill the casks. Sections through older gela- 

 tinous bodies appear to be divided from the edges of the sheaths 

 into chambers in which the curved cell-rows lie (3). When the 

 development is completed, and the nutrient solution exhausted, 

 the gelatinous sheaths deliquesce, the cell-rows separate, and 

 most of the cells die. But previously to this single cells, not 

 occurring in any particular order in the row, develope into 

 distinct spores, becoming a little larger than the rest, and sur- 

 rounding themselves with a firm non-gelatinous membrane, the 

 outer coat of the spore (c). It was from these spores that we 

 set out in the description ; but every living portion of a filament 

 that from any cause becomes separated from the connection 

 may develope into a new gelatinous body. The vegetating 

 protoplasmic bodies are, according to van Tieghem, o- 8-1-2 /x 

 in thickness, the sheaths 6-20 fi, the spores 1-8-2 /x. 



In the germination of the spore the gelatinous sheath origi- 

 nates {e) as a newly formed inner layer of the cell-wall, or by the 

 considerable increase in thickness of a pre-existing inner layer ; 

 the outer coat of the spore then bursts into pieces. This shows 

 decisively that the sheath is a product of assimilation, a growing 

 part of the growing filament. The gelatinous substance has 

 the same chemical composition as the mucilage of viscous fer- 

 mentation. The material for its formation is of course supplied 

 by the sugar of the solution. In van Tieghem's cultures 

 of Leuconostoc in a solution of glucose, air being admitted 

 and the fluid prevented from becoming strongly acid, about 

 40 per cent, of the sugar which disappeared was expended 

 in the formation of the Leuconostoc itself ; the greater part of 

 the remainder was converted by combustion into carbonic acid 



