16 Ingvar Jorgensen and Walter Stiles. 
By saponification with hot alkali isochlorophyllins are formed 
which are fluorescent. They are complex magnesium compounds 
of phytochlorin e and phytorhodin g. On the addition of acid to 
the isochlorophyllins, these two important dissociation products 
are themselves formed. 
The process can also be effected by addition of acid first and 
subsequent saponification with hot alkali. 
The following scheme may help to make clear the relations 
between these various derivatives in the case of chlorophyll a. An 
exactly similar scheme may be made for the case of chlorophyll b. 
[Mg N 4 C 32 H 30 0](COOCH 3 )(COOC, 0 H 3 9 )->[N 4 C 32 H 32 O](COOCH,)(COOC J0 H, 9 ) 
With acid 
chlorophyll a phaeophytin a 
[MgN 4 C 3J H 30 0](COOH)(COOH)---> [N 4 C 32 H 32 0](COOH)(COOH) 
With acid 
isochlorophyllin a phytochlorin e 
The relation between chlorophyll and isochlorophyllin is not 
as simple as that expressed in the above scheme as the alkali not 
only saponifies the two ester groups but also produces an alteration 
in the lactam ring grouping, as indicated by the appearance of the 
brown phase. 
Another difference between saponification with cold alkali and 
with hot alkali is that during the latter process the yellow pigments 
are destroyed. If water is added after the saponification and the 
solution shaken up with ether, the ether should remain colourless. 
We have gone into the explanation of the changes taking place 
in this experiment in some detail, because importance attaches 
to the two dissociation products phytochlorin e and phytorhodin g. 
It was the formation of these substances that led Willstatter 
to the discovery that phseophytin, and also chlorophyll, is a mixture 
of two components. The experiment, moreover, is also of importance 
as a modification of the method is used in the quantitative 
estimation of the green pigments in the leaf. 
Experiment 9. Substitution of other metals for the magnesium 
in chlorophyll. 
Two c.c. of an ether solution of chlorophyll are shaken with a 
