L56 F. X. WILLIAMS 



work of cytoplasm. The nuclei, though Large, are not so sharply 

 outlined. Furthermore, many of the blue-staining proteid bodies 

 have disappeared. Vogel ('13) in speaking of the contents of 

 the fat cells of Lampyris larvae, mentions these albuminous 

 granules as the chief inclusions. This reserve material he says, 

 much resembles in staining and refraction the yolk spheres in the 

 egg. He describes the transformations of the albuminous inclo- 

 sions of the fat cells into the photogenic granules as follows, 

 P . 331: 



Von Wichtigkeit ist nun das Schicksal dieser Dotterkiigelchen in 

 den zur Bildung der Leuchtorgane bestimmten 'Fettzellen.' Dieselben 

 werden namlichwohl unter Einwerkung von Enzymen — zerstrummert, 

 wobei Yacuolen (Wasser?) in ihnen auftreten. Die Bruchstucke werden 

 sodann immer k'einer, und schliesslich komnit es dahin, dass wir in 

 den Licht produzierenden Leuchtzellen nur ganz feine eosinophile 

 Granula vorfinden, dass wohl, da sie sich in jedem Leuchtgewebe der 

 Lampyriden finden, den 'Leuchtstoff' raprasentieren diirften. 



I have been unable to account for the disappearance of the 

 blue-staining proteid granules (albuminous inclusions) in this 

 manner. It seems to me as if they were first dissolved and used 

 up as food and that the smaller, photogenic inclusions were but 

 the indirect product of the first, just as this reserve material 

 contributes to the formation of various tissues in other parts 

 of the body.) The outer photogenic (peripheral) cells — those 

 which are the seat of luminescence — are already larger than 

 those of the scarcely differentiated upper or reflector layer. 

 Nerves, presumably from the last two abdominal ganglia (as in 

 Photinus marginellus, as described by Townsend) and supplying 

 the photogenic tissue, were found at about this stage. They 

 were few in number and quite slender. A single branching 

 nerve extended to a tracheal invagination and could be followed 

 up to the photogenic tissue, which it penetrated. Bongardt 

 ('03) states that in Lampyris splendidula he found nerve fibres 

 in the tracheal end-cells. Geipel ('15), who gives good detailed 

 descriptions and illustrations of the light-organs of Photinus 

 marginellatus and Pyrophorus noctiluca, has found in the former 

 insect a fine nerve penetrating the tracheal end-cells and going 



