18 /ngvar Jorgensen and Walter Stiles. 
The compounds formed by the magnesium free derivatives 
with other metals are unstable towards acids, and require other 
conditions for their formation. Thus phytochlorin e in methyl 
alcoholic solution gives, with water-free barium hydroxide in excess, 
a barium compound. Even compounds with the alkali metals can 
be formed in a similar way, the compounds with potassium being 
the least stable of them all. 
The magnesium compound occupies a place in the middle of 
the series as regards stability, the two extremes being the copper 
and potassium compounds. 
Experiment 10. The action of chlorophyllase. 
Fresh leaves of a species rich in chlorophyllase (Heracleum, 
Galeopsis) are finely divided and put in a 70% acetone solution, 
3 c.c. of solution being used for every gram of leaf powder. The 
chlorophyll, by means of the chlorophyllase, is dissociated into 
phytol and the acid chlorophyllide. This can be demonstrated 
after about a quarter of an hour if the solution is diluted with water, 
transferred to ether and shaken with 0'05% sodium hydroxide. The 
sodium hydroxide takes up more colouring matter the further the 
enzyme action has progressed. 
Experiment 11 . Destruction of chlorophyllase. 
If fresh leaves of a species rich in chlorophyllase are first 
steeped in boiling water for a few minutes before they are placed in 
the acetone solution, unaltered chlorophyll is extracted which does 
not react with dilute alkali. 
The action of the enzyme chlorophyllase consists in either an 
alcoholysis (in alcoholic media) or hydrolysis (in aqueous media). 
For instance, in methyl alcoholic media, the phytol group is 
replaced by a methyl group according to the equation 
(C 32 H 30 ON 4 Mg) (COOCH.,) (COOC 20 H 39 ) + CH 3 OH = 
C 20 H 39 OH + (C 32 H 30 ON 4 Mg) (COOCH 3 )(COOCH 3 ). 
Phytol. Methyl chlorophyllide. 
In aqueous solutions hydrolysis takes place with the formation of 
free acid chlorophyllide 
(C J2 H 30 ON 4 M S )(COOCH S )(COOC 20 H,, 9 ) + H 2 0 = C 20 H 39 OH 
+ (C 23 H 30 ON 4 Mg) (COOCH 3 ) (COOH). 
Chlorophyllide. 
Experiments 10 and 11 demonstrate the hydrolysis of chlorophyll 
and also indicate that it is an enzyme action. Chlorophyllase is a 
