14 



leads to the following experiment, only adapted to the variety of B. polymyxa which 

 produces voluminous slime and grows strongly on malt-wort. 



The bacterium densely sown on cane-sugar-kaliumphosphate-agar, containing 

 but few nitrogen compounds, may form fairly large colonies consisting, however, 

 almost entirely of the strongly swollen walls of the cells. By addition to the said me- 

 dium of a few drops of complete food, for example a little broth or malt-wort, con- 

 taining an excess of sugar, the slime walls grow surprisingly so that the plate covers 

 with a relatively thick slime coat. This slime is built up of the sugars by one or more 

 synthetically acting enzymes, that might be named ,,cyteses" and should be consider- 

 ed as the genes or factors of the cell- walls. 



This slime has the remarkable property of being able to become itself a source of 

 carbon food, but only at the moment when all the cane sugar and all the assimilable 

 nitrogen compounds have been used. If at this time some such nitrogen compound 

 as ammoniumsulphate or asparagin are brought on the slime coat of the plate, the 

 bacteria begin anew to grow and produce new protoplasm from their own cell-walls. 

 This leads to the peculiar consequence, that an auxanogram is produced sinking deep 

 into the layer of slime. For, by the growth the bulk of the bacteria is diminished, be- 

 cause the walls, which chiefly consisted of water and were very voluminous, disappear 

 and are replaced by living protoplasm. So the appearance of the auxanograms is 

 quite changed when compared with the original state, for by their intense increase 

 the opaque bacteria produce an also opaque auxanogram, whilst the original slime 

 was transparent like glass. This proves that, in this case at least, the biological func- 

 tion of the slime is that of a reserve food. 



In this experiment cane sugar was the food for the slime production; as hereby 

 inversion takes place, glucose and levulose are probably the building materials of the 

 slime; that these sugars are assimilated was stated above, and that glucose may also 

 serve for the described experiment we ascertained particularly. 



The other sugars have not yet been extensively examined from this point of view, 

 but it seems that all give the same result. This leads to the conclusion that probably no 

 more than two or three factors or genes (endoenzymes) are active in the production of 

 the cell- wall. The problem is evidently of theoretic interest and deserves nearer research. 



The wall-substance, which certainly belongs to the cellulose group and therefore 

 may be called cellulan, must have a high power of attraction for water, for else its 

 surprising volume cannot be explained. Nevertheless its molecules cannot be very 

 small as they cannot diffuse at all in water. It is not colored by jodine, nor is it at- 

 tacked by diastase. But as B. polymyxa may use it as a food-substance, this species 

 evidently can excrete an enzyme which dissolves it. It is not improbable that this 

 enzyme is pectinase, but this question is not yet answered. Should this really prove 

 to be true, then the other question arises whether the so-called pectose of the central 

 lamellum of the tissues of the higher plants may not also be a cellulose modification, 

 as it is also easily dissolved by pectinase. This view seems to be much more acceptable 

 than the current hypothesis: the central lamellum should be the calcium salt of an 

 acid, isomeric with arabin-acid. 



On the great similarity between pectinase and the seminase of the seeds of the 

 Leguminosae, I already earlier directed the attention. That the latter enzyme does 

 not attack true cellulose is in accordance with the same property of pectinase. 



