112 CHEMlSTh'Y or BAVTKltl \ AM) THEIR I'UODLCTH 



cliomically demonstrable lipiiis. Analyses of dififereiit bacteria show a 

 relatively low content of lipins as i-oiajjared with tubercle bacilli, vary- 

 ing from 1.7 per cent in B. suhtilis to 8.5 per cent, in staphylococci 

 (Jobling and Petersen).'-'-' However, the degree of unsaturation of 

 the fatty acids is less with tuhei-clc liacilli than with other bacteria 

 examined by these authoi's. Extensive studies of bacterial fat stains 

 are rej)()rted by Eiseiilxn'g,-'' but ])ractically nothing is known of the 

 character of the fally or lipoid cDnslituonts of l)a('teria outside the 

 acid-fast grou]). 



Spores diil'er from llicir jiareiil l)acteria in containing a nuich 

 greater proportion of the solid constituents and less water. In molds 

 Drymont found that the spores contained over 60 per cent, of dry 

 substance, and almost all the water was so held as to resist drying 

 by temperatures below boiling; the dry substance is very rich in 

 protein and poor in salts. As the spores may lose their chromatin 

 content without loss of capacity to propagate, it would seem that this 

 is not a nuclear chromatin but merely a reserve food supply.-""'^ The 

 wall of the spore consists of a "cellulose-like" substance and a very 

 hygroscopic extractive matter. The great resistance of spores to dry- 

 ing and to heat can be readily understood in view of these facts. They 

 contain, and perhaps secrete, active enzymes (Eifront).-'^ Flagella 

 also soom to be composed of a relatively condensed protein. 



Staining Reactions. — The staining reactions of bacterial cells are 

 much as if the bacteria consisted entirely of chronuitin, so that at 

 one time the theory prevailed that bacteria consisted merely of a 

 nucleus and a cell wall, without any true cytoplasm. The demon- 

 stration of abundant nucleoprotein in the contents of bacterial cells 

 explains their staining affinity for basic anilin dyes. Owing to some 

 unknown differences in composition, not all bacteria are stained 

 equally well by the same basic dyes. Although the staining of bac- 

 teria depends upon a chemical reaction between the nucleoproteins and 

 the basic dye, yet the combination is not usually a firm one, being 

 readily broken by weak acids in most cases. That the decolorization 

 of bacteria depends u})oii dissociation of the dye-])roteiii couiponnd 

 is shown by the fact that absolutely water-free alcohol will not de- 

 colorize dry bacteria, nor do water-free alcoholic solutions of dyes 

 stain dehydrated bacteria. 



Gram's ^NFetiiod of staining has been ascribed to llie format ion 

 of an iodiii-])ararosanilin-protein compound which is not easily disso- 

 ciated b\' water' in the case of bacteria that stain b\" tins nu^thod, and 

 which is readily dissociated and dissolved out in the case of bacteria 



24.1 .Tour. Ivs]). Mfd.. 1!II4 CJO). 4.")(t. 

 2-' Vircliow's .Arcliiv., 1!>1(I (1!»!M. ">n2. 

 2-.a Ruzifka, ("cnt. f. l?al<t.. 1014 (41). (Ul. 

 20Mon. 8c. QuOTiu'villc. 1007, p. SI. 



