E. NEWTON HARVEY 273 



thick layer of vaseline. This procedure is not necessary in the case 

 of lucif erase. 



The salivary diastase was fresh filtered saliva, and the yeast in- 

 vertase a fresh filtered extract of yeast ground with sand. All 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; all were supplied by the Digestive Ferments Co. of Detroit. 

 The three latter preparations probably contained proteolytic enzymes 

 although they did not digest fibrin under the same conditions with 

 which they were tested with the photogenic substances. The erepsin 

 in neutral solution did not digest fibrin to any extent, or albumen, 

 but tryptophane was produced from Witte's peptone. 



Since both acid and alkali injure luciferase and alkali causes a very 

 rapid oxidation of lucif erin, some difficulty was experienced in work- 

 ing with pepsin, active only in acid, and with trypsin, most active in 

 alkaline 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 luciferase. Presumably such neutral solutions would also 

 digest lucif erin if it were capable of digestion, but the results indi- 

 cate that it is not. Pepsin could only be tested on luciferase with an 

 amount of HCl lower than the optimum, otherwise the HCl 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 recorded 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 I 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 ac- 

 tion. The commercial preparations of pancreas (pancreatin) usually 

 contain some lipase (steapsin) and diastase (amylopsin), but as sal- 

 ivary diastase (ptyalin) and malt diastase did not digest luciferase 

 and a sample of trypsin lacking lipase did digest luciferase, the de- 

 structive power of various pancreatin and steapsin preparations is 



