COMPOSITION OF MORPHOLOGtCAL COMPONENTS 59 
are greater in the carbohydrate-containing mediinn. This decrease 
in the nitrogen content in pathological bacteria grown in sugar media 
may be of considerable importance, particularly in the preparation of 
vaccines and other antigens. Nothing is known definitely of the dis- 
tribution of nitrogen in bacteria, but this reduction of 25 per cent in 
the nitrogen content may well influence somewhat the immunizing 
value of vaccines. 
C. COMPOSITION OF THE MORPHOLOGICAL COMPONENTS OF 
THE BACTERIAL CELL. 
1. Cell Membrane.— Typical cells of higher plants contain cellu- 
lose, and bacteria were formerly differentiated sharply from the plant 
kingdom because cellulose could not be found in them. Later observa- 
tions would suggest that cellulose or substances chemically closely 
related to it are demonstrable in certain bacteria.^ Dreyfuss- appears 
to have identified cellulose in bacteria from pus and in B. subtilis; 
Hammerschlag^ claims to have isolated cellulose from tubercle bacilli ; 
Dzierzgowski and Rekowski^ appear to have found cellulose in diph- 
theria bacilli; more recently Tamura^ has demonstrated a hemicellulose 
in the same organism. On the other hand, many observers have cast 
grave doubts upon the matter, and it is still unsettled. 
Emmerling'^ identified chitin in Bacterium xylinum, and Iwanoff' 
gives the following percentage composition of the cell membranes of 
B. pyocyaneus, B. megatherium and B. anthracis: C, 46 per cent.; 
H, 6.7 to 7 per cent; N, 8.4 to 8.8 per cent; which is empirically very 
similar to chitin. Viehover^ has made similar observations. Chitin 
is chemically a polymer of glucoseamine, CH20H.(CHOH)3.CHNH2.- 
CHO, which in turn is an amino hexose very similar to glucose, except 
that it has an amino group adjacent to the aldehyde group. Chitins 
are characteristically animal in origin, and are rarely, if ever, found in 
typical plants, hence the distribution between cellulose and chitin in 
bacteria is important as suggesting relationships to the vegetable or 
animal kingdoms. 
Many bacteria stain browm with iodine, and the assumption is that 
the cell membrane of such organisms, or the cell substance contains 
substances similar to glycogen. According to iVrthur Meyer, ^ many 
bacteria color blue with very small amounts of iodine; brown or red- 
brown with an excess of iodine; indicating that there is a very small 
1 Emmerling: Ber. d. deut. chem. Gesell., 1897, 32, 541. Winterstein : Ztschr. f. 
Physiol. Chem., 1895-1896, 21, 134. 
2 Ztschr. f. physiol. Chem., 1894, 18, ,358. 
' Monatschr. f. Chem., 1899, 10, 9. 
* Arch. Soc. Biol., St. Petersburgh, 1892, 1, 167. 
5 Ztschr. f. physiol. Chem., 1914, 89, 289. 
6 Berichte deutsch. chem. Gesell., 1899, 32, 541. 
' Hofmeister's Beitrage, 1902, 1, 524. 
8 Ber. d. deutsch. botan. Gesell., 1912, 30, 443. 
9 Flora, 1899, 86, 428. 
