56 The Production of Light by the 



emulsion of luminous bacteria. It is greener than Cypridina, which 

 looks blue in lamplight and decidedly blue in the dark. Examined 

 with a Zeiss comparison microspectroscope, the spectrum extends, 

 in the case of both fish if Hghting brightly, from about X = 0.45 

 to X = 0.64 micron. When brightly lighting, the red end is distinctly 

 visible; when somewhat dimmed from lack of oxygen no red can 

 be seen, but only a strip of greenish blue. There are no dark or bright 

 bands, but a continuous spectrum is formed. 



CYTOLYSIS. 



A luminescent extract of the photogenic gland of Cypridina made 

 with sea-water is quite unaffected by the ordinary cytolytic agents. 

 There is neither extinction of light nor increased brightness on mixing 

 with fresh water, on saturation with chloroform, or on addition of 

 small amounts of saponin or sodium glycocholate, or on slight warm- 

 ing. By these means cells are caused to swell and become more or 

 less completely fluid, many of the granules within the cell dissolving 

 at the same time. 



A luminous extract of pennatulids {Cavernularia, Ptylosarcus) or 

 of jelly-fish {^quorea, Mitrocoma) becomes much brighter on appli- 

 cation of cytolytic agents, and then the light disappears completely 

 and can not be resuscitated in any way. Either some photogenic 

 cells in the extract, which are still intact, cytolyze with liberation 

 of photogenic material and production of hght, or photogenic granules 

 in the extract dissolve with, production of light. 



The light of an emulsion of luminous bacteria, on the other hand, 

 is immediately extinguished by the above-mentioned cytolytic means, 

 without any preliminary increase in brightness. Light-production 

 is dependent upon an intact bacterial cell, and when bacteriolysis has 

 occurred the photogenic pow^r is lost completely. 



Both Anomalops and Photohlepharon extracts behave toward 

 cytolytic agents as an emulsion of luminous bacteria. The light 

 disappears on addition of three volumes of fresh water, but not on 

 addition of three volumes of isotonic salt or cane-sugar solution. 

 A drop of chloroform added to a test-tube of luminous emulsion puts 

 out the light immediately, as does also a pinch of saponin or of sodium 

 glycocholate, the latter more readily than the former. There is no 

 initial increase in brightness in the case either of the bacteria or 

 of these fish. 



Like an emulsion of luminous bacteria, the light disappears from 

 an extract of Anomalops photogenic organ, if crystals of cane sugar, 

 MgS04. or (NIl4)2S04 are added, but returns if the mixture is imme- 

 diately diluted with sea-water, most readily and bright in the case 

 of the cane sugar. Addition of alcohol also causes a reversible ex- 

 tinction. As this behavior toward sugar and salts is similar to that 



