48 SECTIONAL ADDRESSES, 
change into the red colouring-matters. Everest has shown that reduc- 
tion is the process actually involved and that flavonols are the pre- 
cursors of anthocyans, not vice versa as suggested by other investi- 
gators; moreover, he found (1918) that ‘ Black Knight ’ petals contain 
a glucoside of delphinidin, whilst the corresponding flavonol, myricetin, 
is present in the sap, also as a glucoside: 
OH 0.Cl 
O 
Bo NHN SNe ga WP 
OH 
WA > egy Oni WN OH 
Myricetin. Delphinidin Chloride. 
Hence it will be seen that pelargonidin, cyanidin, and delphinidin, 
corresponding to the three above-mentioned phenolcarboxylic acids, are 
the fundamental materials in the group of anthocyan pigments, and 
that they are derived from the three flavonols, kaempferol, quercitin, 
and myricetin respectively. The variations upon these types which 
present themselves in blossoms are twofold, due to (1) the number and 
position of entrant methyl groups, and (2) the number and character 
of the aldose molecules which go to form their glucosides. Belonging 
to the first group are peonidin (monomethylated cyanidin), ampelop- 
sidin, myrtillidin, and petunidin (monomethylated delphinidin) with 
malvyidin and oenidin (dimethylated delphinidin). The second group 
arise from combination with glucose, galactose or rhamnose, the 
greatest proportion of pigments occurring as mono- or diglucosides. 
Thus callistephin and salvinin are the mono- and diglucoside of pelar- 
gonidin ; asterin and chrysanthemin are monoglucosides and idaein a 
galactoside of cyanidin, derived from which are the diglucosides cyanin 
and mekocyanin, and the rhamnoglucoside, keracyanin; violanin is a 
rhamnoglucoside of delphinidin, whilst delphinin, when hydrolysed with 
hydrochloric acid, yields delphinidin chloride, glucose and p-hydroxy- 
benzoic acid in the molecular proportion, 1: 2: 2. 
Thus may the chemist find fresh delight in the hedgerow and the 
garden by reflecting on the processes which lead to molecular structures 
lying well within his mental horizon, and adorning those familiar models 
with all the chromatic splendours of snapdragon, pansy, rose, and 
larkspur. The gustatory and esthetic thrill engendered in consuming 
summer pudding and custard is heightened by the soothing blend of 
egg-yolk lutein and the crimson contributed to the colour scheme by 
the raspberry and currant anthocyanins. 
Micro-Biochemistry. 
Amongst the many sources of pleasure to be found in contemplating 
the wonders of the universe, and denied to those untrained in scientific 
principles, is an appreciation of infra-minute quantities of matter. It 
may be urged by some that within the limits of vision imposed by 
telescope and microscope, ample material exists to satisfy the curiosity 
of all reasonable people. but the appetite of scientific inquiry is in- 
satiable, and chemistry alone, organic, inorganic, and physical, offers an 
