LIGHT-PRODUCING ORGANISMS 3 



thought the light of the sea was electric, because it was 

 excited by friction. ... I shall not trespass on the 

 time of the Society to refute the above speculations ; their 

 authors have left them unsupported by either arguments 

 or experiments, and they are inconsistent with all ascer- 

 tained facts upon the subject. The remarkable property 

 of emitting light during life is only met amongst animals 

 of the four last classes of modern naturalists, viz., mol- 

 lusca, insects, worms, and zoophytes..'* MacCartney 

 recognized the true cause of the light, although he had 

 little idea of the vast number of marine forms which are 

 luminous and omits entirely any reference to the fishes, 

 many of which produce a light of their own when living, 

 apart from any bacterial infection. 



A survey of the animal kingdom discloses at least 36 

 orders containing one or more forms known to produce 

 light and several more orders containing species whose 

 luminosity is doubtful. In the plant kingdom there are 

 two groups containing luminous forms. The distribution 

 of luminous organisms is brought out in the accompanying 

 classification of plants and animals. Those orders are 

 printed in italics which contain species whose self -lumi- 

 nosity is fairly well established. It will be noted that 

 further subdivisions into orders is not given in classes 

 of animals which lack luminous forms. 



TABLE 1 



DISTRIBUTION OF LUMINOUS ORGANISMS IN PLANT AND 



ANIMAL KINGDOMS 



Plant Kingdom 

 I. Thallophyta 

 Algae 



Cyanophyceae (Blue-green Algae) 

 Chlorophyceae (Green Algae) 



