282 E. NEWTON HARVEY. 



was able to make out the limits are the same for both JEquorea 

 and Mitrocoma, perhaps a somewhat narrower band for the latter. 



The light of these jelly fish only appears on stimulation or on 

 dissolution of the cell. It appears on handling or electrical 

 stimulation, or when the jelly fish is carried by the current 

 against some objects in the water. On merely touching a jelly 

 fish one cannot observe that any luminous secretion is definitely 

 thrown into the water as in the case of Cypridina, but on very 

 gentle stroking of the edge of the umbrella a mass of luminous 

 material comes off which adheres to the fingers, or on tossing an 

 animal on the surface of the water, abundant luminous material 

 is liberated which causes the sea water to luminesce. It appears 

 that the luminous material comes off in the slime so commonly 

 secreted by these organisms. A similar behavior is exhibited 

 by the Pennatulid, Cavernularia. It would seem that this is to be 

 interpreted as an extracellular luminescence, although not so 

 marked a one, certainly, as that of Cypridina. There remains, 

 however, the possibility that we have here cells very easily 

 ruptured, with discharge of their contents into sea water. 



The luminous material of &quorea, Mitrocoma or Phialidium 

 can be dried over CaCl 2 and will give a bright light when again 

 moistened. 



A strip of the margin of the umbrella of sEquorea or Mitrocoma 

 is easily cut off with scissors, giving a mass of tissue containing 

 as little non-luminous material as it is possible to obtain. If this 

 is squeezed through four layers of cheesecloth, there is obtained 

 a luminescent extract which glows for some hours. In one case 

 the light was still visible after nine hours. This extract behaves 

 just as a similar one prepared from Cavernularia (2). When 

 the luminescence disappears on standing, the addition of fresh 

 water, gentle heating or cytolytic agents such as saponin, sodium 

 glycocholate, chloroform, ether, or NaCl crystals again calls 

 forth the luminescence. Tannic acid, strychnin, or phloridzin 

 do not cause the light to reappear. Once the light has been 

 caused to disappear by addition of saponin or Na glycocholate 

 powder, the further addition of fresh water will cause no more 

 light to appear. 



Isotonic cane sugar solution does not call forth the production 



