The Chemistry of Light-Production in Luminous Organisms. 207 



agents, Na 2 2 , KMnO 4 , etc. The blood of certain invertebrates also 

 causes very faint light-production, but we can not be sure that this is 

 not due to the fact that the blood is somewhat less concentrated than 

 sea-water, although the determinations of other closely allied forms 

 show the salt-content to be the same as the sea- water in which they live. 



CHEMICAL REACTIONS. 



The luminous juice of Cavernularia contains the luminous substance, 

 but mixed with many substances, so that mere chemical tests on 

 the juice are of no value in determining the chemical nature of the 

 luminous substance. The luminous material is salted out along with 

 the other proteins, but does not retain its power to phosphoresce 

 long enough to be manipulated by the ordinary chemical methods. The 

 following paragraphs give the results of precipitation by (NH 4 ) 2 S0 4 , 

 picric acid, alcohol, etc. 



If to the fresh filtered luminous juice of Cavernularia we add sugar, 

 NaCl, MgS0 4 , (NH 4 ) 2 S0 4 to saturation, or 5 volumes of glycerine, the 

 light disappears. A heavy precipitate forms in (NH 4 ) 2 S0 4 , a small 

 precipitate in MgSO 4 and practically none in NaCl. The precipitates 

 are soluble in sea-water. No precipitate is formed in sugar or glycerine. 

 If poured into fresh-water or sea-water immediately after the light has 

 disappeared, light is produced by all solutions. If the tubes are allowed 

 to stand for a day, no light is produced by any tube on pouring into 

 fresh-water or sea-water. 



If alcohol or acetone (3 vols.) is added to the juice, a precipitate 

 forms and the light disappears. The precipitate is insoluble and gives 

 no light in sea-water or fresh-water. 



The alkaloidal reagents picric acid, phosphotungstic acid, and 

 tannic acid immediately cause precipitation with disappearance of 

 light. The precipitates are insoluble in sea- water or fresh-water and 

 produce no light. 



Normal acetic acid or n NH 4 OH, added drop by drop, produce no 

 precipitate, although the light disappears in weak concentrations. 



ANESTHETICS. 



Ether, chloroform, and benzol cause a fairly rapid disappearance of 

 the light in the order named, the ether most rapid. In turpentine, 

 chloral hydrate, thymol, and chloretone the light stays for a long time 

 and then disappears. There is no reappearance of light from any of 

 the tubes if poured into fresh-water or sea-water unless we do so imme- 

 diately the light has disappeared, and then the light is very faint and 

 momentary. 



In other words, the juice can not be anesthetized. Even in concen- 

 trations of alcohol, ether, chloroform, or butyl alcohol, which cause a 

 slow disappearance of light, there is no recovery or only a momentary 



