An enzyme histochemical and electron microscopical study of the light organ of the glow-worm, Lampyris noctiluca.

The light organs of female specimens of the glow-worm Lampyris noctiluca were investigated by enzyme histochemical tests, lipid stains, and electron microscopy. Differences, both histochemical and in fine structure, were found between the cells of the photocyte and reflector layers. The photocytes contained a vesiculated reticulum, photocyte granules, amorphous granules, and numerous mitochondria. The reflectcr layer did not contain the reticulum or the two types of granules and there were fewer mitochondria. Glycogen granules, and spaces possibly caused by the removal of urate during preparatory procedures, were present in this layer but absent from the photocytes. All the dehydrogenase enzymes, except for glucose-6-phosphate, 6 phosphogluconic, lactic, and /3-hydroxybutyric dehydrogenases, which were absent from both layers, showed more activity in the photocyte layer. NADH2 and NADPH2 diaphorase showed no activity in the reflector layer. A transition zone between the two layers was demonstrated both histochemically and morphologically. Alkaline and acid phosphatase could not be demonstrated in the light organ. The adenosine triphosphatase demonstrable in the organ was not activated by magnesium but was activated by calcium ions. Lipid was present in both layers of the organ. The tracheolar supply to the photocytes was good but no tracheolar end organs were observed. The dehydrogenase activity of the body musculature is also reported upon.