FOOD RELATIONSHIPS OF BACTERIA 65 



II. FATTY SUBSTANCE OBTAINED BY EXTRACTION WITH 



CHLOROFORM, POSSESSES THE FOLLOWING 



CHARACTERISTICS : 



Melting point 46 C. 



Acid number ' 23.08 



Reichert-Meissl number 2.007 



Hehner number 74 . 236 



Saponification number 60.70 



Ether number 36 . 62 



Iodine number (according to Hubl) 9 . 92 



III. THE FATTY SUBSTANCE OBTAINED BY EXTRACTION WITH 

 CHLOROFORM CONTAINS: 



Per cent. 



Free fatty acids 14.38 



Neutral fats and esters of fatty acids 77.25 



Alcohols separated from the fatty acid esters (with melting point 



43.5-44 C.) 39.10 



Lecithin 0.16 



Cholesterin Not determined 



Substances directly soluble in water 0.73 



Substances soluble in water which are formed by the complete 



saponification of the fatty substances 25 . 764 



Inorganic Constituents. The most conspicuous inorganic element 

 found in the ash of bacteria is phosphorus, and the content of phos- 

 phorus, recovered as phosphoric acid, frequently reaches as high as 

 half the total ash weight. It is probable that a considerable part of 

 this phosphorus is combined with nucleic acid to form nucleo-protein. 



4. Spores. The chemical composition of spores is not well deter- 

 mined, but the generally accepted theory is that they contain relatively 

 less water and consequently a greater proportion of proteins and ash. 

 Reinke 1 has suggested that the sporoplasm is an anhydride of the 

 cytoplasm of the vegetative cell. Sporulation implies that relatively 

 considerable amounts of water must be taken up by the spore sub- 

 stance in order to regain the proportion of this substance found in the 

 parent organism. 



D. FOOD RELATIONSHIPS OF BACTERIA. 



1. General. Food is any substance which a living organism may 

 utilize, either by making it a part of its living material or as a source 

 of energy. Food which is suitable for utilization by any organism must 

 contain all the elements necessary for the building up and maintenance 

 of that organism. Analyses of bacterial cells, which have been given 

 in preceding tables, show them to be made up of the same elements 

 as those of the higher plants and animals; viz., carbon, hydrogen, 

 oxygen, nitrogen, and phosphorus, together with smaller amounts 



1 Quoted by Kruse, Allgem. MikrobioL, p. 57, 



