PHYSIOLOGICAL LIGHT. 429 



mercury, etc., immediately suppress the luminosity, which fails to 

 reappear when water is added. 



The antiseptics, phenol and thymol, and many other antiseptic and 

 antizymotic substances extinguish physiological light. Reducing agen ts, 

 such as tbe sulphydrates, sulphites, and hydrogen, suspend the photo- 

 genic property. It is also extinguished by the action of a vacuum or 

 by shaking the photogenic liquor with animal charcoal; the light reap 

 pears on agitation with air. Oxidizing reagents, such as ozone, oxygen- 

 ated water, and pure oxygen, even at a pressure of several atmospheres, 

 do not increase the intensity of the luminous phenomenon; on the con- 

 trary, the action of energetic oxidizing reagents at once and finally 

 extinguishes the light without first causing any increase in its luster. 



Cold — that is to say, a temperature of —15° C. — does not finally 

 destroy the photogenic power. The light which disappeared on the 

 freezing of the liquid reappears with unabated intensity after melting. 

 Heat excites and hastens the appearance of the light, whose intensity 

 increases up to 30°, remains nearly constant from 30° to 55°, then 

 decreases to finally disappear at 60°. Electricity acting upon the saline 

 luminous liquor contained in a U tube induces a series of interesting 

 phenomena. The light first grows pale and is soon extinguished at the 

 negative pole. At this instant the positive pole begins to be obscured, 

 and a moment afterwards only the lower part of the U tube shinrs. 

 When the liquor at the two poles is extinguished and the current is 

 reversed the light reappears in the branch in which the positive pole is 

 placed, but it does not always reappear at the negative pole. There 

 are produced during electrolysis about the electrodes liocculous depos- 

 its in which there may be distinguished granulations having the aspect 

 of more or less modified vacuolides. It is easy to show that the liquor 

 ceases to shine at the negative pole because of nascent hydrogen while 

 it is extinguished at the positive pole, in spite of the presence of nas- 

 cent and ozonized oxygen because the liquid becomes strongly acid. 



All these reactions, as well as many others which I pass over, suffi- 

 ciently prove that we have to deal with a protoplasmic substance whose 

 spontaneous destruction may be retarded, but not completely sus- 

 pended, and which behaves toward reagents as do ferments, whether 

 figurate or not; as do viruses; in a word, as does living matter 

 reduced to its simplest expression, living, but yet incapable of repro- 

 duction while in that condition. This protoplasmic living matter, after 

 it has dissipated in the form of light the energy that animated it, 

 becomes changed to a crude, crystalline substance, and this is death. 



The constant coexistence of these colloidal and crystalloidal sub- 

 stances caused me to think that one of them acted upon the other to 

 produce light, but a more profound study showed me that the crystal- 

 line substance was only a transformation of the protoplasmic substance, 

 to which I gave the name luciferase. 



This transformation takes place under the influence of life, water, 

 and a suitable temperature. 



