Suberin and Cutin 
21 
His original paper must be consulted for details of his methods, 
but the results may be summarised as follows: 
He established the presence of several organic acids, which he 
termed as a class the suberogenic acids. Some of these acids, notably 
phellonic acid and phloionic acid, he obtained pure and crystalline. 
He found traces only of one higher alcohol, glycerine, and gave 
reason for thinking that the suberogenic acids were present in 
suberin in other forms than that of glycerides. 
Gilson gives full details of his manipulatory methods, which have 
been followed throughout in a repetition of the work in the laboratory 
by several workers. His statements have all been confirmed even as 
to approximate yield obtained, save that so far we have failed to 
isolate sufficient quantities of glycerine to obtain the crystalline 
glycerine tribenzoate with benzoyl chloride and thus place beyond 
doubt the production of glycerine as a result of saponification. 
In any case, Gilson concluded from the small quantities of 
glycerine obtained on saponification, and from the insolubility of the 
original suberin in normal fatty solvents, that suberin could not be 
regarded as a typical fat. 
Kugler (11) had previously shown that some 12 per cent, of solid 
matter could be extracted from cork by boiling chloroform, of which 
some 2-9 per cent, was the crystalline substance cerin previously 
referred to (p. 19). The rest of the substance extracted proved to 
be amorphous and Kugler considered it to be suberin. Explaining 
his inability to extract the rest of the suberin by assuming that it 
was protected from the action of the fatty solvent by the molecules 
of cellulose which enveloped it, and assuming solubility of suberin 
in fatty solvents, Kugler decided that it was to be regarded as a 
true fat. 
Although suberin is known to stain with fatty stains—notably 
Sudan III (see Kroemer (10) for an elaboration of this staining method) 
and Scarlet Red (Scharlach R)—Gilson’s conclusion above seems 
soundly based and suberin cannot be regarded as a true fat 1 . There 
remain two outstanding questions, in what form are the suberogenic 
acids present in suberin and do they unite in the formation of a 
single definite substance suberin or is suberin an aggregate formed 
from varying quantities of these suberogenic acids? 
As already stated Gilson obtained two of these acids crystalline 
1 Schmidt (14) has confirmed the presence of a small proportion of glyce¬ 
rides in suberin and suggests that the suberogenic acids originally reach the 
lamella in this form, subsequently decomposing and releasing the suberogenic 
acids. 
1—11 
