Note 10 — Chapter I · NATURE’S INSURGENT SON

The phosphorescent disease of the sand-hopper (Talitrus) is described by Giard and Billet in a paper entitled ‘Observations sur la maladie phosphorescente des Talitres et autres Crustacés,’ in the memoirs of the Société de Biologie, Oct. 19, 1889. Billet subsequently gave a further account of this organism, and named it Bacillus Giardi—after Professor Giard of Paris. (Bulletins scientifiques de la France et de la Belgique, xxi. 1898, p. 144).

It appears that the parasite is transmitted from one individual to another in coition. The specimens studied by Giard and Billet were obtained at Wimereux near Boulogne. I found the disease very abundant at Ouistreham near Caen in the summer of 1900. I have not observed it nor heard of its occurrence on the English coast. Sea-water commonly contains a free-living phosphorescent bacterium which can be cultivated in flasks of liquid food so as to give rich growths which glow like a lamp when the flask is agitated so as to expose the contents to oxidation. This bacterium is not, however, the cause of the ‘phosphorescence’ of the sea often seen on our coasts. That is due in most cases to a much larger organism, as big as a small pin’s head, and known as Noctiluca miliaris.