194 



Papers from the Department of Marine Biology. 



nothing from the dried tissue and leave the photogenic material un- 

 harmed. Indeed, the material may be extracted with boiling ether 

 for 24 hours without impairing its power to phosphoresce. Boiling 

 alcohol does destroy the power to phosphoresce, and the nature of its 

 action is discussed below. These results, as well as the previous experi- 

 ments of McDermott (20 and 21) and Dubois (22), using fresh watery 

 material, show conclusively that the photogenic substance is not a fat 

 or fat-like body of any kind. The results are given in table 9, which 

 also gives the time of extraction and the temperature. 



Table 9. 



Substance. 



Temperature 

 (in degrees). 



Time 



(in hours). 



Extracted 

 material. 



Extract 



evaporated 



in vacuo. 



Ether (cold) 



Ether (hot) 



Chloroform (cold) 



Chloroform (hot) 



Ethyl alcohol (cold) 



Ethyl alcohol (hot) 



Ethyl alcohol and ether (equal parts) 



boiling 



Carbon tetrachloride 



Carbon disulphide 



Acetone 



Toluol 



Amyl alcohol 



Ethyl butyrate 



20 

 35 

 20 

 61 

 20 

 78. 



44 

 20 

 20 

 20 

 20 

 20 

 20 



72 

 24 



24 

 24 



10 



48 

 48 

 48 

 48 

 48 

 48 



+ 



+ 

 Very faint' 

 Very faint' 



'The material was washed with ether to remove the amyl alcohol and ethyl butyrate. 



A plus sign indicates phosphorescence when water is added and a 

 minus sign indicates no phosphorescence. Both the original extracted 

 material and the residue of the filtered extract evaporated to dryness 

 were examined. The results indicate not only that the photogenic 

 substance is not a fat, but also not a lecithin. I am aware that the 

 lecithins are difficult to extract in toto from the cell, but this can be 

 accompUshed by a mixture of hot ether and alcohol, and yet a mixture 

 of hot ether and alcohol will extract nothing which Avdll phosphoresce 

 from the firefly powder. We may safely say that the photogen is 

 not a lecithin. 



Of all the solvents tried, only hot alcohol and cold am.yl alcohol and 

 ethyl butyrate gave results that would indicate a possible solution of 

 the photogenic substance; and yet there is nothing in the evaporated 

 filtrate that will phosphoresce when water or a neutralized 3 per cent 

 solution of H2O2 is added. Thinking that a second substance might 

 be necessary and that this had not been extracted by the fat solvents, 

 although the photogen had, the filtrate was also tested by adding a 

 water extract of firefly organs, fresh or preserved with toluol or chloro- 



