LECT. VIII. 



PHOSPHORESCENT MATTER. 



171 



In my ignorance of this science I content myself with an- 

 nouncing to zoologists the presence of this body.* 



Chemical Nature of the Phosphorescent Matter. I will 

 not now detain you longer than is absolutely necessary, in 

 our examination of the chemical nature of the phosphores- 

 cent matter. This substance, taken from the living animal, 

 has a remarkable odour, resembling that of the sweat of the 

 feet. It is neither acid nor alkaline ; it dries readily in the 

 air, appears to coagulate on contact with acids diluted with 

 water ; does not perceptibly dissolve either in alcohol, or 

 ether, or in weak alkaline solutions. It dissolves and be- 

 comes changed, in hot concentrated hydrochloric and sul- 

 phuric acids. By the employment of the last-mentioned 

 acid, the solution does not become blue, which fact ex- 

 cludes the idea of the presence of albumen. Heated 



* I subjoin figures of the luminous organs in two species of Lampyris, 

 viz. L. lucida and L. noctiluca : the latter is the common glow worm of 

 England. 



Fig. 9. 



Phosphorescent Organs of Glow-worms. 



No. 1. is an enlarged view of the in- 

 ferior surface of the abdomen of the 

 Lampyris noctiluca after the integument 

 had been removed. 



a a a. Represent the three masses of 

 luminous substances which are applied 

 to the three last rings of the abdomen. 



bbb. The arrangement of cellular or 

 intestinal substance on the other abdo- 

 minal rings, which gives the pale colour 

 to the body of this insect. 



Nos. 2. and 3. are the sacs of the 

 common glow-worm, prodigiously mag- 

 nified to show their structure. Fig. 3. 

 is cut open to expose the luminous mat- 

 ter it contains. The coat of the sac is 

 still seen to preserve its figure. The sacs 

 are formed of two layers or membranes, 

 each composed of a transparent silvery 

 fibre. The sacs are more minute than 

 the head of the smallest pin, and are 

 placed on the last abdominal ring. J. P. 



