The Chemistry of Light-Production in Luminous Organisms. 203 



light which make the field of view look like the starry heavens. If 

 water is added to this sea- water juice, the light is greatly increased, 

 due to the appearance of numerous additional points of light. These 

 points of light come from minute granules and globules easily visible 

 in the filtered juice under the microscope. The addition of water to 

 a dark Cavernularia juice which has stood for two days will cause the 

 appearance of light due to the dissolving of the granules and globules. 

 So sensitive are they to the addition of water that 1 drop of fresh- water 

 added to 5 c.c. of juice will produce light, and so bright is the light that 

 the addition of 1 drop of Cavernularia juice to 5 c.c. of fresh-water 

 produces a light easily visible when the drop is mixed with the 5 c.c. 



By centrifuging the filtered juice, the granules may be partially 

 thrown down and will give a brilliant light if fresh- water is added, 

 while the liquid itself (turbid in appearance) gives a much fainter 

 light. No light is produced upon the addition of water to a parchment- 

 paper sea-water dialysate of the juice, so that light-production is 

 undoubtedly connected with the visible globules and granules of the 

 juice. That it is connected with the solution of the granules is indi- 

 cated by the fact that fresh-water but not salt-water or isotonic cane- 

 sugar is able to call forth the production of light. The process appears 

 to be similar to the cytolysis of cells, as can be observed by an inspec- 

 tion of table 8, which shows the effect of adding various substances 

 to the dark juice of Cavernularia. 



The light-giving granules of Cavernularia will pass through an alun- 

 dum filter crucible (R A 84) of the finest pores, but not through a 

 Pasteur-Chamberland filter-tube. The liquid passing through the 

 latter is perfectly clear and non-luminous and gives no light when 

 water is added. 



There is no adsorption of the light-producing substance by bone- 

 black or Fe(OH) 3 . 



ELECTRICAL STIMULATION. 



The juice of Cavernularia filtered through filter paper does not re- 

 spond to the strongest interrupted induced shocks. The living colony, 

 however, responds readily. 



When a galvanic current is passed through one of the excised polyps 

 mounted between non-polarizable electrodes, a flash of light occurs on 

 the make and a series of flashes while the current is passing, which 

 cease on the break. There is no flash of light on the break. A similar 

 response can be observed with Noctiluca (2). It will be remembered 

 that Romanes (25) observed a series of contractions in the bell of a 

 medusa during the passage of a galvanic current, and the sartorius 

 muscle of the frog often contracts on the make of a galvanic current, 

 remains contracted during the passage of the current, and relaxes on 

 the break. 



