go Lectures on Bacteria. [^ ix. 



very like M. Ureae and forming rows of bead-like cells ; by itself - 

 it produces viscidity and mannite in the cane-sugar solution with 

 separation of carbonic acid. Secondly, cells of irregular shape 

 and somewhat larger size than those of the Saccharomyces of 

 beer-yeast (see page 98), and with morphological peculiarities, 

 •which the descriptions which we have of them do not at all 

 clearly explain ; these cells are at all events not Bacteria, and 

 are said to cause viscidity only and to form no mannite in the 

 cane-sugar solution. The viscous substance itself, of which we 

 are here speaking, is stated to be a carbohydrate with the for- 

 mula of cellulose (C^ Hj„ O5). 



From these data, which it is true are still very imperfect, it 

 must be acknowledged that the disengaged carbonic acid and the 

 mannite are products of fermentation ; but the viscous substance 

 itself is more probably to be placed in the category of muci- 

 lagino-gelatinous cell-membranes, which are so common in Bac- 

 teria and Fungi and which we have already observed so often 

 in connection with the Zoogloeae ; it is therefore not a product 

 of the fermentation of the nutrient solution, but of the assimi- 

 lation of the organism which excites the fermentation. 



This view is distinctly supported by the history of the 

 development and vegetation of Leuconostoc mesenterioides, the 

 frog-spawn-bacterium of sugar-manufactories, examined by Cien- 

 kowski and van Tieghem, which has the power of converting 

 large casks of the juice of the sugar-beet in a short space of 

 time into a mucilagino-gelatinous mass and thus of causing 

 considerable loss. Durin saw a wooden vat containing fifty 

 hectohtres of a 10 per cent, solution of molasses become filled 

 with a compact Leuconostoc-jelly in less than twelve hours. The 

 development of Leuconostoc was mentioned above on page 22 as 

 an example of an arthrosporous course of development, but a 

 more detailed description of it must now be given. See Fig. 11. 



The round spore-cell {d) germinates in a nutrient solution, 

 and appears at first to be surrounded by a gelatinous envelope 

 several times thicker than the spore itself («). Then a simple 



