808 Wisconsin Academy of Sciences, Arts, and Letters. 
methanone configuration, or contains the “chromone” group 
does not appear to have been determined. Since it contains 
two additional hydrogen atoms as well as the additional oxy¬ 
gen the former appears more probable, that is, the elimination 
of the elements of a molecule of water to form a heterocycle 
probably has not taken place. 
The remaining pigments from Rkamnus cathartica plainly do 
not fall under this formula of saturation, therefore, will not be 
considered here. 
Pigments referable to hydrocarbons of the degree of sat¬ 
uration C n H 2n - 14 . 
All of the pigments of known constitution falling under this 
degree of saturation fall into two closely related classes. 
I. Derivatives of diphenyl and its homologues. 
II. Derivatives of diphenyl methane series and their homo¬ 
logues. 
Not only are the pigments referable to these closely related 
hydrocarbons but they are all hydroxy or methoxy—derivatives 
of these hydrocarbons. They occur in the plant either in 
the free state or as glucosides, and they resemble each other as 
closely in properties as they do in general structure. 
I. Pigments referable to the diphenyl series and homologues. 
1. Pigments referable to ditolyl. 
a. Ellagie acid. 
II. Pigments referable to diphenyl methane series and their 
homologues. 
A. Diphenylmethane series. 
1. Pigments referable to diphenyl methane. 
Cotoin. 
Euxanthone. 
Maclurin. 
Kinoin. 
Gentisein. 
Gentisin. 
Datiscetin. 
2. Pigments referable to phenyl-o-ethophenyl- 
methane. 
Catechin 
Cyanomaclurin. 
