130 



BIOCHEMICAL STUDIES OF PHYLOGENY 



CH 3 



CH— CH 2 .CH 2 R 



Cholesterol 



Cholestanol 



CH 3 



CH— CH 2 CH 2 R 



CH 3 

 CH.CH 2 .CH 2 .R 



CH 3 

 CH.CH=CH.R 



Clionasterol 



Porifasterol 



CH 3 



CH — CH=CH.R 



Stellasterol 



Fig. 39. Sterol structure. This figure shows the structure of various 

 of the sterols mentioned in the text. 



R = — CH 2 .CH(CH 3 )<, for Cholesterol and Cholestanol. 

 R = -CH.(CH 3 ).CH"(CH 3 ) 2 for the others. 



of a vestibule in the ophiuroids. On p. 700 she states, " Finally, in 

 recent years workers in comparative biochemistry have produced 

 striking evidence in favour of this community of ancestry " (i.e. 

 the ophiuroids with the echinoids and not with the asteroids). 

 " Bergman (1949 and in a letter) finds that all ophiuroids and 

 echinoids tested have sterols of Type I, namely cholesterol or some 

 closely related compound, whereas numerous asteroids tested have 

 Type II sterols that is, stellasterol or related compounds. The 



