LIPIDS PRESENT IN LUNG TISSUE 787 



steam-volatile, optically active, and branched. The main constituent of 

 this group was found to be methylhexanoic acid. A large proportion of 

 liquid, optically active, branched-chain acids having C 9 to ds were also 

 present. The higher non-volatile acids included palmitic, stearic, and an 

 unsaturated Cis acid. The solid acids were not branched. However, the 

 secretion did not contain provitamin D 3 (7-dehydrocholesterol), as was 

 formerly believed. 417 



Wheatley 442,443 concluded that ovarian dermoid cyst fat differs signifi- 

 cantly from human sebum. Free fatty acids are absent, and n-paraffin 

 hydrocarbons occur only in traces in the cyst fat. On the other hand, 

 n-alcohols such as eicosanol are present in much larger amounts in the cyst 

 fat than in sebum. It is suggested that the cyst fat is sebum in which 

 the formative process has not been completed. As noted earlier Kop- 

 penhoefer 403 reported the presence of squalene in ovarian dermoid cysts. 



10. Lipids Present in Lung Tissue 



Bloor 23 reported the following lipid composition of moist lung tissue of 

 cattle: lecithin, 0.68%; cephalin, 0.57%; acetone-soluble fraction, 0.76% ; 

 and unsaponifiable fraction, 0.25%. Thannhauser et al. 36 further analyzed 

 the phospholipid components in normal human lungs. These workers 



Table 24 



The Lipid Components in the Fluid from the Respiratory Tract 



of the Rabbit, Cat, and Dog" 



Lipid concentration in mg./lOO ml. 

 Substance determined Rabbit Cat Dog 



Total lipid 65 60 197 



Neutral fat 18 12 53 



Total fatty acids 42 33 126 



Cholesterol 



Total 13 19 41 



Ester 8 12 28 



Free 5 7 13 



Phospholipid 28 22 85 



a E. M. Boyd, S. Jackson, M. MacLachlan, B. Palmer, M. Stevens, and J. Whittaker, 

 J. Biol. Chem., 153, 435-438 (1944). 



found that, in the dried lung tissue, the total phospholipids amounted to 

 6.65%, while lecithin was present to the extent of 3.85%, cephalin to that of 



442 V. R. Wheatley, Nature, 168, 1128-1129 (1951). 



443 V. R. Wheatley, Biochem. J., 53, xxi (1953). 



