428 PHYSIOLOGICAL LIGHT. 



microscope, and which are found in all photogenic elements, must be 

 the plasmatic or microsomic corpuscles of the luminous cells. 1 They 

 are seen to undergo a series of metamorphoses in proportion as their 

 photogenic power becomes exhausted (fig. 3). 



Like all protoplasm undergoing catabolic changes — or, to express it 

 otherwise, passing from life to death — these granulations lose, with the 

 energy which they emit, their colloidal nature, passing to the crystal- 

 loidal state. But the photogenic protoplasmic matter survives the 

 animal and continues to shine and palpitate for quite a long time after 

 somatic death. It is even possible to retard its spontaneous destruc- 

 tion and to suspend the emission of light by covering the luminous 

 organs with powdered bichromate of soda. There is then formed a 

 peculiar liquor, which becomes luminous upon the addition of water 

 and its agitation in contact with air. Immersion in vinegar produces 

 the same result, and the light may be made to reappear after several 

 days by adding ammonia. But there is no method by which it can be 

 indefinitely preserved. The most advantageous means are those used 

 for preserving pancreatic ferments. The luminous organs sprinkled 

 with very dry, finely powdered carbonate of lime are dried in an oven 

 at 36°. After drying they are separated from the inert powder and 

 macerated in absolute alcohol and ether at 60°. Thus treated, these 

 luminous organs may be relighted by contact with water after a very 

 long, but not an indefinite time. This experiment shows, first, that 

 the photogenic substance is not a fatty matter soluble in alcohol and 

 ether, as has been supposed, and, second, that it is spontaneously 

 destroyed at length, in spite of all precautions against such a result. 

 It thus behaves exactly like certain viruses, such, for example, as 

 vaccine matter. Although absolute alcohol does not destroy it, dilute 

 alcohol does, and, like many microorganisms, it can, when quite dry, 

 resist a temperature of 120°, but in the presence of water its photogenic 

 power is destroyed at 60°. 



In order to clearly show that the cell and the photogenic matter are 

 independent, the organs prepared as I have just indicated should be 

 triturated and the luminous liquid thus produced filtered; with this 

 liquid a certain number of reactions may be obtained which I will 

 succinctly state. 



Solutions of acids or of energetic bases when sufficiently concentrated 

 destroy the luminosity immediately, so that it does not reappear upon 

 neutralizing the liquid. A great number of neutral chemical com- 

 pounds, such as the chlorides of sodium, magnesium, and potassium, 

 sulphates of sodium, magnesium, etc., dissolved in sufficient quantity 

 in the liquid, suspend the emission of light, which, however, reappears 

 upon the addition of a sufficient quantity of water. All the reagents 

 which coagulate albuminoid substances, such as tannin, bichloride of 



1 See Anatornie et physiologie de la Pbolade dactyle: Aimales de l'Universitd de 

 Lyon, II, fasc. 2, 1892. Published by Masson, Paris. 



