404 BACTERIOLOGICAL CHEMISTRY 



CH3 I /^^3 



CH2 ! CH— CH(CH2)3CH 



/\ ^^ \CH 



CHg C CH2 



^H3 I I I 



CH2 I CH CH CHj 



CHg C CH 



HO.CH C CHj 



\ /% / 

 \/ %/ 

 CHo CH 



dihydrocholesterol, oxycholesterol (in which the double 

 bond is saturated by hydrogen and oxygen respectively) 

 and ergosterol, 



CH2 CH 



give cross -reactions, the reactions with homologous sera, 

 however, being stronger than with heterologous sera. 

 Cholestan (in which the hydroxyl group of cholesterol is 

 replaced by a hydrogen atom), dibromocholesterol (in 

 which the double bond is saturated by bromine) and 

 cholesterol esters showed differences from one another, 

 due to differences at the doul)le l)ond or the hydroxyl 

 group, but also gave cross-reactions due to the rest of 

 the molecule. 



