TRAUGOTT BAUMGARTEL 17 



per cent solution color volutin quite intensively, while eosin borax carmine and nigrosin 

 do not stain it; safranin and Bismarck brown give a stronger color to volutin than to 

 the cytoplasm. 



As with the protein materials, so with the carbohydrates of bacteria — little defi- 

 nite investigation has as yet been done. Most of the work up to the present has con- 

 cerned itself with the study of the carbohydrates in the composition of bacterial mem- 

 branes and mucus. For example, the gelatin formed by Streptococcus mesenterioides 

 has been analyzed. The purified masses of gelatin were extracted with 96 per cent al- 

 cohol, then boiled for a rather long time with milk of lime and the thickened masses 

 obtained in this way precipitated with carbonic acid. From the precipitated calcium 

 carbonate the mucous solution was poured off, cleared with hydrochloric acid, and 

 precipitated with alcohol. The substance thus obtained is called "dextran." It ap- 

 pears that neutral lead acetate does not precipitate the concentrated dextran solution, 

 while basic lead acetate produces a pastelike mass. Moreover, it happens that a heat- 

 saturated solution of barium hydroxide precipitates from concentrated dextran solu- 

 tion an oily substance, and Fehling's solution, without itself being reduced, precipi- 

 tates a mucous substance. When boiled with dilute sulphuric acid, dextran goes over 

 into dextrose slowly; when heated to 120° C, it goes over in a few hours. 



Here may also be mentioned the researches on the carbohydrate content of the 

 pellicle which appears in cultures of Bad. xylinum. The leather-like colonies were 

 first cleansed with water, then boiled with a 20 per cent caustic potash, washed with 

 dilute hydrochloric acid or with water, and finally treated with bromine. In this way 

 there were produced colorless, transparent, thin films which dissolved in ammoniacal 

 copper oxide as well as in concentrated sulphuric acid and, by element analysis, 

 showed the composition corresponding to the formula CcHioOj. When the film was 

 dissolved in concentrated sulphuric acid and this solution — after preliminary dilution 

 with water — boiled, neutralized with barium carbonate, and filtered, its reactions in 

 regard to dextro-rotation and reduction power were like dextrose. 



The carbohydrates of the bacteria that are demonstrable by microchemistry are 

 glycogen and iogen (granulose), which appear in the protoplasm of many cells as 

 colorless, viscous-flowing masses. Glycogen and iogen differ microchemically in their 

 behavior with iodine. If very dilute potassium iodide-iodine solution is added to bac- 

 teria which contain glycogen and iogen, only the iogen wiU be colored at first (blue) ; 

 with stronger iodine solution the glycogen will also take (a dark red-brown) color. If 

 the carbohydrate of the bacteria is colored only red brown, then it consists solely of 

 glycogen ; if, with a stronger iodine-KI solution it takes only a blue color, then only 

 iogen is present. If carbohydrate-containing bacteria are boiled for five minutes in 

 water, the carbohydrates are still demonstrable by means of iodine-KI solution. If 

 pigmented carbohydrate-containing bacteria are boiled in water, they appear without 

 color when examined on the warm stage of a microscope. On the other hand, they 

 again show color when the iodine-KI solution is cold. If bacteria containing carbohy- 

 drates are treated for three minutes with boiling concentrated sulphuric acid, the car- 

 bohydrates are completely dissolved.' 



' For a discussion of polysaccharides ("specific soluble substances") from bacteria, of. chap, lii (by 

 Drs. Zinsser and Mueller) in this volume. 



