344 Observations on Phycoerythrin. 
from time to time. A trace of eucalyptus oil was added to each as 
antiseptic. 
The milk after eight hours gave no coagulation on adding 
dilute acid, and with the Biuret test gave a rose colour instead of 
the violet given by fresh milk. 
The phycoerythrin lost its colour and gave finally a practically 
colourless, slightly opalescent, solution. 
This solution was evaporated to a sirup and examined micro¬ 
scopically for tyrosin and leucin. No tyrosin could be found, but 
there appeared to be a very little leucin. The amount of phy¬ 
coerythrin in 50 c.c. of solution is, however, very small (two litres 
give about ‘5gms. of crude phycoerythrin), so that the amount of 
hydrolysed products could not be great. 
Hydrolysis by Acids.— *5 gtrts. of solid phycoerythrin (middle 
fraction) was boiled for twenty-four hours with 50 c.c. dilute 
sulphuric acid (one vol. cone. H 2 S0 4 to nine vols. water), the 
solution filtered from a small residue, neutralised with barium 
carbonate and again filtered. The filtrate and washings were 
concentrated to a sirup. 
The residue on examination under the microscope gave no 
signs of tyrosin, but a good amount of characteristic leucin crystals. 
Chemical tests gave slight reactions for tyrosin, but confirmed the 
idea that leucin was in far the greater amount. 
Conclusions. 
The above results appear to show :— 
(1) . That phycoerythrin plays the part of assistant to chloro¬ 
phyll by absorbing blue-green light and degrading it to the light 
which corresponds to the absorption bands I. and III. of 
chlorophyll. 
(2) . That phycoerythrin is probably a colloidal nitrogenous 
substance, related to protein—but not a true protein, as its nitrogen 
content is too low and it does not give the Biuret reaction. The 
evidence is incomplete ; pure phycoerythrin has still to be pre¬ 
pared and even comparatively pure phycoerythrin in sufficient 
quantity for extended chemical investigation has not yet been 
obtained. 
The cost of this research has in part been defrayed by a grant 
of £15 from the Grant for Research made by the Treasury to 
University College, Reading. 
I am glad to take this opportunity of expressing my indebted¬ 
ness to Dr. Keeble, who suggested this piece of research, and has 
taken a most helpful interest in the progress of the work, 
