148 PHOSPHORIC INSECTS. 
United States. The species described by Illiger 
(in vol. 1. of Annals of Nat. Hist. Soc. of Berlin) 
were taken im the Brazils, Peru, Buenos Ayres, 
Chili, Cuba, St. Domingo, and Guiana. At St. Do- 
mingo, where these insects are abundant, the in- 
habitants call them Cucwij. They are often apphed 
to useful purposes, as lights, as decorations, and 
especially to destroy gnats which swarm in the 
dwellings. Considerable quantities are taken to 
this effect in the month of June. 
On examining the luminous tissue in Lampy- 
ris noctiluca, Hlater noctilucus, and later ignitus, 
Macartney observed that this tissue only differed 
by its yellow colour from the greasy intercellular 
substance which is found in other portions of the 
insect’s body. In H. noctilucus and LH. ignitus 
the light proceeds from masses of this substance 
closely applied underneath the transparent parts 
of the insect’s skin. When the season for giving 
light is passed, this yellow tissue is absorbed and 
replaced by the ordinary intercellular tissue. In 
Lampyris noctiluca, besides this greasy tissue, the 
same author observed, in the last abdominal seg- 
ment, two small oval sacs formed by an elastic 
spiral fibre, containing a soft yellow greasy sub- 
stance of closer texture than that above-mentioned, 
and affording a more brilliant hght than the rest 
of the luminous tissue.* ‘The hight emitted by 
* Philosophical Transactions, 1810. 
