THE LIPOIDS OF MICRO-ORGANISMS 373 



optically active hydroxy-acids esterified with carbo- 

 hydrates together with smaller amounts of true waxes 

 which are esters with higher secondary alcohols. Phthio- 

 cerol, a crystalline alcohol, m.p. 73°, [a]D-4-8° (in 

 chloroform), C35H72O3, containing two hydroxyl groups 

 and one methoxy group, is found in all the wax fractions 

 of human and bovine tubercle bacilli but not in those of 

 other acid-fast bacteria. Avian tubercle bacilli, the 

 Timothy grass bacillus and the leprosy bacillus contain 

 the secondary alcohols fZ-2-eicosanol, CH3.(CH2)i7.CHOH. 

 CH3, m.p. 62°, [«]d+4-2°, and f/-2-octadecanol, 

 CH3.(CH2)i5.CHOH.CH3, m.p. 56°, \a]u-^5-l\ The wax 

 of the human tubercle bacillus contains the specific 

 polysaccharide, to which fatty acids are attached ; 

 avian tubercle bacilli, and the Timothy grass bacillus 

 contain trehalose, whilst the leprosy bacillus gives only 

 glycerol as the water soluble product of hydrolysis. 



The properties of the various waxes are summarised 

 in Table 24. 



