168 KOLLIKER, ON LAMPYRIS. 
II. PuystoLoGicaL. 
8. The proper luminous substance does not consist in the 
granules of the white cells, or the so-termed “ luminous 
granules” of Leydig, under which that author also includes 
some larger, radiated, opaque granules in the cells of the 
adipose body in the female of L. splendidula, but in the con- 
tents of the pale cells, as may be readily proved by direct 
observation of the luminous organs under the microscope by 
night, when the light of the lamp is shut off. 
9. The contents of these luminous cells correspond, in all 
their microscopical reactions, with an albuminous material ; 
although, owing to the extremely minute quantity of the 
substance which can be obtained, it has been impossible to 
subject it to a more satisfactory chemical examination. 
10. With respect to the granules contained in the white 
cells, as well as to the larger radiated globules in the cells of 
the adipose body described by Leydig, not merely and erro- 
neously as luminous granules, but also as composed of an 
inorganic matter, probably phosphorus! the simplest mi- 
cro-chemical examination shows, that they consist of a uric 
acid salt, which, so far as my experiments have hitherto 
shown, represents urate of ammonia (NH,O, Ur). On the 
addition of acetic or hydrochloric acid, the characteristic 
crystals of uric acid are very speedily formed; whilst with 
caustic soda and potass beautiful acicular bundles of the cor- 
responding urate are produced. In fact, if two or three of 
the luminous organs in L. splendidula are isolated by simple 
dissection, the murexid-test, by means of nitric acid and 
ammonia, may be directly applied, and will supply the most 
convincing proof of the true nature of their contents ; and on 
the subsequent addition of potass the characteristic purple- 
blue colour. will be obtained. The production of the arbo- 
rescent crystallization of sal ammoniac on the addition of 
hydrochloric acid, and the circumstance that no residue is 
left when the white substance is heated to redness, determine 
that the base of the uric acid salt in question is ammonia._ 
11. All endeavours to detect the presence of phosphorus 
in the luminous organs were fruitless. The organs of thirty 
males of L. splendidula were treated with sulphuret of carbon, 
and when this was allowed to evaporate on blotting paper, 
no luminosity was evident, nor was the paper charred. When 
organs which have been isolated by dissection are treated 
with nitrate of silver, no black precipitate is formed. The 
same was the case when a number of the insects were placed 
