CHEMICAL COMPOSITION 78 



From later studies it seems probable that substances 

 resembling the albumin of higher forms do not occur in 

 bacteria, at least in appreciable quantities. Globulin has 

 been reported by Hellmich in an undetermined bacterium, 

 but is certainly not commonly found. The larger portion 

 of the protein is of a comparatively simple type, in fact, 

 consists of protamins most of which are in combination 

 with nucleic acid as nucleoprotamins. Practically all recent 

 workers find a high percentage of nuclein, both actually 

 isolated and as indicated by the amounts of purin bases — 

 xanthin, guanin, adenin — obtained, as well as by the abun- 

 dance of phosphorus in the ash, already mentioned. Some 

 of these nucleins have been shown to have poisonous 

 properties. 



Closely related to but not identical with the proteins are 

 the enzymes and toxins which are formed in the cell and 

 exist there as endo-enzymes or endotoxins respectively. 

 These substances will be discussed later under the heading 

 "Physiological Activities of Bacteria" (Chapter XII). 



Carbohydrates are not commonly present in the cell con- 

 tents, though glycogen has been observed in a few and a 

 substance staining blue with iodine in one or two others. 

 This latter substance was at first considered to be starch 

 " granulose," but is probably more closely related to glycogen. 



Fats seem to be very generally present. The commoner 

 fats — tri-olein, tri-palmitin, tri-stearin have been found by 

 many analysts. The "acid-fast bacteria" are particularly 

 rich in fatty substances, especially the higher wax-like fats. 

 Lecithins (phosphorized fats) and cholesterins (not fats but 

 alcohols) have been repeatedly observed and probably occur 

 in all bacteria as products of katabolism. 



Organic acids and esters occur as cell constituents but 

 will be discussed in connection with their more character- 

 istic occurrences as products of bacterial activity, as will 

 also pigments which may likewise be intracellular in some 

 instances. 



The following analysis of tubercle bacilli, from de 

 Schweinitz and Dorset, while not intended as typical for 

 all bacteria, still illustrates the high percentage of protein 



