255 



as B. megatherium and also the common hay bacterium B. mesentericus, but only if 

 fed with cane-sugar. The levulan arises in two ways ; it either remains in contact and 

 entirely united with the bacterial body as a slimy cell-wall, in which case on cane- 

 sugar-agar plates strongly swelling colonies develop, or the levulan is deposited outside 

 the bacterial body at some distance from the colony. If the latter takes place the 

 remarkable reaction occurs which I have called the emulsion reaction *). Its ex- 

 planation was given by the discovery of a specific exoenzyme, viscosaccharase, which 

 acts on cane-sugar and converts it into levulan slime, which is incapable of diffusion 

 hut attracts water, so that droplets are formed causing a strong swelling of the agar. 

 This enzyme, acting synthetically and evidently polymerising the cane-sugar, might 

 as well be called saccharo-levulanase and is obviously one factor of the factorcomplex 

 that governs the cell-wall formation. That it is not the only one follows from the fac.t 

 that some levulan bacteria, for instance the hay bacterium itself, when fed with other 

 sugars, produce another not slimy wall-substance, probably cellulose, which likewise 

 derives from cane-sugar beside levulan, but only in slight quantity. If the production 

 of cellulose is brought about by one or more factors is not yet known. As to the visco- 

 saccharase, however, there is not the least doubt but that it consists of one single 

 enzyme or factor. 



Hence it may be concluded that it is quite well possible to become acquainted with 

 the separate factors of a process at first sight so complicated as the formation of the 

 cell-wall, and it may safely be predicted that further experiments will show whether 

 the cellulose production also depends on one single or on more than one enzyme. 



On the other hand, at the factor analysis by crossing experiments with higher 

 plants and animals, without the guidance of the enzyme conception, we are continually 

 in doubt whether a factor, thought to be elementary, will not, on continued examina- 

 tion, prove to be composed of other still unknown factors. 



As to dextran I have stated elsewhere 2 ) that it is a wall substance comparable to 

 levulan, likewise only resulting from cane-sugar, but produced by some lactic acid 

 ferments, belonging to the physiological genus Lactococcus. Dextran, however, never 

 originates independently from the cell, as may occur with levulan, but exclusively .it 

 the surface of the outer layer of the protoplasm and in direct contact with it. But 

 the knowledge of the relation between levulan and its producing enzyme, viscosac- 

 charase, indicates clearly that dextran, whose properties are so analogous to those of 

 levulan, must have a similar origin. It is therefore most probable that dextran also 

 arises under the influence of one single factor or specific enzyme, which might be 

 called saccharo-dextranase, but which, being an endoenzyme, cannot leave the cell. 



The formation of the slime wall by B. prodigiosum viscosum 3 ) must be brought 

 about by at least two factors, differing from levulanase and dextranase since the 

 slime produced by this bacterium, belongs to the celluloses or cellulan-slimes. That 

 beside the slime factor, which might be called cellulanase and which produces cellulan 



') These proceedings 9 February and 2 Mei 1910. Folia microbiologica Bd. i pag 

 382, 1912. 



2 ) Die durch Bakterien aus Rohrzucker erzeugten Wandstoffe. Folia microbiologica. 

 Bd. i, page 392, 1912. 



s ) B. prodigiosum viscosum is no natural form but a mutant or race, easily obtained 

 rom B. prodigiosum. Folia microbiologica, Bd. i, pag. 35, 1912. 



