FULQORIN.E. 9 



the attendants on travellers in China are in the habit 

 of lighting their ways at night by carrying one Fulgora 

 candeUaria on the foot, and another in each hand. 



The Editors of the above Magazine hint that '' if 

 Fulgora be luminous, then it must studiously turn off 

 its * bull's eye ' in the presence of all the modern 

 scientific naturalists who have made special search for 

 its lamp ; and having arrived at this stage of develop- 

 ment we anticipate that, by a process of natural 

 selection, Fulgora will eventually lose all luminous 

 power and attributes, having found no (?) truth in the 

 motto " ex luce lucellum." 



Though much has been written on the cause of 

 luminosity in insects and fish, the interest is yet fresh, 

 and much remains to clear up certain points. There 

 is no a priori reason against a Cicada showing luminous 

 properties, and negative evidence is but slight proof 

 against positive assertion. 



On account of the interest in this subject I may 

 quote some of Dr. Dubois' observations. He has 

 lately studied the subject of insect luminosity. So far 

 as concerns the phenomenon in the American Fijro- 

 j)horus voctilucens, he states that the light is not brought 

 into play by mere oxidation of matter in the luminous 

 organs. Pure oxygen gas does not increase the light, 

 neither is it affected by moderately compressed air. 

 He seems to think that the light is useful for the 

 insect's guidance ; for if the organs on one side are 

 obscured by a black wax, the insect walks in a curve 

 toward the side still illuminated. If the light from 

 both sides be quenched, he says the insect seems to be 

 puzzled, and that the ground is felt doubtfully with 

 the antennae. The light has a peculiar spectrum, and 

 as it is said to affect silver salts it is probably rich in 

 chemical rays. As in other insects, the organs con- 

 tinue to shine long after the death of the insect and 

 their separation from the body. 



It is even stated that the phosphorescence is not 

 destroyed by drying ; for these parts may be powdered, 



