PHOTOGENIC ORGANS OF LAMPYRIDS 151 



layers. The cells are now more irregular in form, and measure 

 about 10-16 micra in diameter. They often contain a few spheri- 

 cal proteid bodies with deeply staining centers. We find that 

 in sections of a second-year larva, the fat cells are much larger 

 and are massed into spherical or subspherical bodies (fig. 24, 

 FB.) which occupy a large portion of the body-cavity. These 

 fat-spheres measure about 60-160 micra in diameter, though 

 they vary considerably in size. Their constituent cells have 

 thin and often ill-defined walls, so that the mass may look much 

 like a syncitium. Each cell has a single oval or subspherical 

 nucleus which is surrounded by a small amount of protoplasm 

 The rest of the cell is filled with blue-staining proteid bodies as 

 well as fewer pale brown ones of the same size. These bodies, 

 which range from 1.16 to 4 micra, are usually spherical, but may 

 also be oblong, or both oblong or crescentic. In addition, very 

 small yellowish-brown granules, resembling coagulated plasma 

 occur in the fat cells. But the fatty substance itself has all 

 been dissolved away in the fixing and staining, and this also 

 appears to be the case with the urates. The fat-body occupies 

 the greater part of the body cavity, where it often appears as 

 a loose and irregular perivisceral sheet. Isolated fat-bodies are 

 also found and seem to be quite similar to those which occur 

 in the larva of Lampyris noctiluca, as figured by Hollande 

 ('09). No breaking up of the fat-spheres, such as is found in 

 pupating larvae and in pupae, was observed. 



Situated especially near the insertions of the dorso-ventral 

 oblique muscle bundles are often more or less compact groups 

 of large haemocytes or blood-cells. These may lie in part on 

 the hypodermis, but they are usually separated from it by a 

 small or even a considerable space, and may sometimes occur 

 near the center of the body. Apparently similar cells have been 

 studied in Apis and Vespa, by Anglas ('00) among others. He 

 does not attribute to them a phagocytic function, but thinks 

 that they may grow at the expense of the degenerating muscle. 

 At any rate they do not appear to be involved in the forma- 

 tion of the photogenic organs. A sagittal section shows clearly 

 that these haemocytes are segmentally arranged. 



