CHEMICAL COMPOSITION 107 



as constituents of the bacterial plasma. The slimy material 

 produced in cultures by some varieties of bacteria is, at least 

 for certain forms, a body closely related to or identical with 

 true mucin. 1 Heirn 2 considers that anthrax bacilli also pro- 

 duce niucin. 



Bacterial Carbohydrates. Likewise the earlier descriptions 

 of cellulose or hemicellulose in the cell membrane of bacteria are 

 undoubtedly incorrect. Numerous investigations have shown 

 that the insoluble bacterial cell wall consists chiefly of chitin, 

 which on being split with acids yields 80 to 90 per cent, of the 

 nitrogenous carbohydrate, glucosamin. The distinction is a 

 very important one, since cellulose is a typically vegetable prod- 

 uct, while chitin is equally typically animal in origin, being 

 found chiefly in the shells of lobsters and crabs, the wings and 

 coverings of flies, beetles, etc. Chitin seems to be an amino- 

 derivative of a carbohydrate, a polymeric form of some simpler 

 compound, just as cellulose is a polymer of a simpler carbohy- 

 drate. 



Other carbohydrates seem to be scanty in the bacterial cell. 

 Cramer could find no glucose in any variety, although there are 

 some bacteria that contain material reacting like starch with 

 iodin. Levene, 3 however, found in B. tuberculosis a substance 

 with the properties of glycogen. 



Bacterial Fats. By staining methods, fats have been recog- 

 nized in many species, and by extraction with fat solvents 

 lecithin, cholesterin, simple fats, and specific bacterial fats have 

 been isolated ; this is particularly true of B. tuberculosis, which 

 owes its characteristic staining properties to the specific fat-like 

 bodies which make up a large proportion of its entire mass. 4 

 Numerous studies of these fats of B. tuberculosis have been 

 made 5 and by using diiferent extractives, from 20 to 40 per 

 cent, of the entire weight of the bacilli has been found soluble 

 in fat solvents. Kresling found that the substance soluble 

 in chloroform had the following composition : 



Free fatty acid 14.38 per cent. 



Neutral fats and fatty acid esters 77.25 " " 



Alcohols obtained from fatty acid esters .... 39.10 " " 



Lecithin 0.16 " " 



Substances soluble in water 0.73 " " 



1 Kettger, Jour. Med. Kesearch, 1903 (10), 101. 



2 Munch, med. Woch., 1904 (51), 426. 

 8 Jour. Med. Eesearch, 1901 (6), 135. 



4 See Camus and Pagniez, Compt. Kend. Soc. Biol., 1905 (59), 701. 



8 For literature see Bulloch and Macleod, Jour, of Hygiene, 1904 (4), 1. 



