534 History of Luminescence 



a storm, and could be very useful to meteorologists in predicting the 

 weather. 



The value of sea light to fishermen in making visible at night 

 the position of schools of fish was particularly noted by D. Lands- 

 borough (1842) , a student of luminous hydroids on seaweed. An- 

 other view was expressed by J. C. Wilcocks in The Sea Fishermen 



(London, 1865: 271) , that " should the ' brine ' or ' fire ' show itself, 

 the fish will not be likely to strike the nets." Phosphorescence occurs 

 in all seas, not necessarily in the tropics but in the Arctic and Ant- 

 arctic as well. Sea light has been observed under the ice at Kiel 



(H. A. Meyer, 1866) and along the west coast of Norway, where 

 W. E. Koch (1882) noted flashes of light as his ship crashed through 

 the ice of Hardangerfjord. He found that, when some of the ice 

 was melted, the resulting water was still luminous. Koch had noticed 

 that the luminescence was greater during atmospheric disturbances 

 and argued that it was partly caused by electricity, although he also 

 reported a connection with the migration of fish and thought that 

 it might have an important bearing on their food. The light was 

 at a maximum in spring and autumn when the waters swarm with 

 embryonic forms. 



Discovery of Luminous Dinoflagellates 



PIONEERS 



Although Macartney described and figured the flagellate, Nocti- 

 luca, he omitted one group of minute luminous organisms, the dino- 

 flagellates proper, particularly responsible for sea light. Their ability 

 to luminesce was as yet undescribed because of their small size and 

 the inadequacy of microscope objectives of the time.^° They are 

 classified in such genera as Ceratium, Peridinium, Gonyaulax, etc. 

 Although Noctiluca actually belongs in this class also, it is a large 

 and aberrant member. The tiny sparkles of light of the sea, whose 

 origin is so hard to identify, are all due to such microscopic dino- 



^^ F. J. Cole in his History of protozoology (1926) attributes the delay in knowledge 

 of unicellular animals to poor microscope objectives, which were not achromatic until 

 1824. Although Leeuwenhoek discovered bacteria, Vorticella and Volvox in 1677, and 

 Paramoecium was anonymously described in some letters sent to Sir C. H. and pub- 

 lished in the Phil. Trans. (No. 284, 23: 1368, for 1703) , the protozoa were only estab- 

 lished as unicellular forms by C. T. E. von Siebold (1804-1885) in his Lehrbuch der 

 vergleichende Anatomie der wirbellosen Thiere in 1845. The word " infusoria " ap- 

 pears to have been used by M. F. Ledermiiller (1719-1769) in 1763 and by H. A. 

 Wrisberg (1739-1808) in 1765 but this designation included diatoms, worms, planaria, 

 rotifers, and other minute multicellular forms. It is no wonder that luminescence of 

 the smaller dinoflagellates was not definitely recognized until the work of G. A. 

 Michaelis in 1830. 



