On the Chemistry of Light Production in Luminous Organisms. 91 
The salivary diastase was a fresh-filtered saliva and the yeast in 
vertase a fresh-filtered extract of yeast eround with sand. All of the 
other preparations were made by dissolving the commercial enzyme 
powder in water. The erepsin was a solution of duodenal scrapings 
dried in vacuo and powdered, and the spleen, liver, and kidney sub- 
stance was a solution of these glands dried quickly in vacuo and 
powdered. The three latter preparations probably contained pro- 
teolytic enzymes, although they did not digest fibrin under the same 
conditions with which they were tested with the photogenic sub- 
stances. The erepsin in neutral solution did not digest fibrin to any 
extent, or albumen, but trytophane was produced from Witte’s peptone. 
Since both acid and alkali injure luciferase and alkali causes a very 
rapid oxidation of luciferin, some difficulty was experienced in working 
with pepsin, active only in acid, and with trypsin, most active in alka- 
line solution. As preparations containing trypsin were found to digest 
fibrin fairly rapidly in neutral solution, they were made up in water, and 
the experiments show that neutral trypsin solutions will digest lucif- 
erase. Presumably such neutral solutions would also digest luciferin 
if it were capable of digestion, but the results indicate that it is not. 
Pepsin could only be tested on luciferase with an amount of HCl lower 
than the optimum, otherwise the HC1 alone is sufficient to destroy the 
luciferase. For this reason the action of pepsin was not so carefully 
investigated, but the result of the one experiment indicates that a slow 
digestion of luciferase occurs. Acid is not so destructive to luciferin, 
and 0.2 per cent HCl plus pepsin was found to possess no digestive 
power. 
It will be noticed from table 1 (page 108) that of all the enzymes tried 
on luciferase only the proteolytic enzymes have any digestive power. 
Trypsin, erepsin, and pepsin HCl all have at least some digestive action. 
The commercial preparations of pancreas (pancreatin) usually con- 
tain some lipase (steapsin) and diastase (amylopsin), but as salivary 
diastase (ptyalin) and malt diastase did not digest luciferase and a 
sample of trypsin lacking lipase did digest luciferase, the destructive 
power of various ‘“‘nancreatin” and “‘steapsin”’ preparations is unques- 
tionably due to their trypsin content. That the destruction of lucif- 
erase is actually due to digestion and not to the injurious action of 
amino acids resulting from the digestion of proteins associated with 
the luciferase is shown by adding to luciferase the products of 4 days’ 
(at 38° C.) tryptic digest of albumen (then boiled to destroy the 
trypsin) and keeping the mixture with toluol at 38° C. for 4 days more. 
The luciferase was found to be unaffected by the amino acids present. 
These experiments all indicate that luciferase is a protein. As 
erepsin has a digestive action, one might suppose that it belongs to the 
group of proteoses, but too great reliance can not be placed on con- 
clusions drawn from the action of erepsin, as this enzyme is said to 
