MUSCULATURE OF CULEX PUNGENS. 295 



with haematoxylin and eosin. From the blue, they pass through 

 a violet to a rose color which markes the necrosis of tissue. 

 Some then give a copper-colored appearance, and finally clear 

 spaces indicate the completion of fatty degeneration. The infer- 

 ence here is that the muscle fragments ingested by the wander- 

 ing cells are carried into the body cavity where they line the 

 body wall, and complete their work. All through the body 

 beneath the hypodermis, and especially between the muscles of 

 the thorax, large numbers of these cells aggregate, where they 

 are seen scattered among free sarcolytes. Figs. 3 and 4 of Plate 

 X. show the condition just described, Fig. 4 being farther ad- 

 vanced. In some instances a nucleus is found centrally located, 

 while at other times it is pushed to the periphery and flattened 

 to the membrane of the cell by the enclosed fragments. Degen- 

 eration seems to take place more rapidly about the nucleus and 

 works gradually to the more distant inclosures. 



Two forms of degeneration have been noted, both of a diges- 

 tive nature, the one extracellular by unseen agents, as if by 

 means of fluids secreted by cells at a distance, or in the muscle 

 itself or some part of it ; the second an intracellular digestion 

 which occurs in the instance of ingestion of muscular debris by 

 phagocytes. In either case the result is the same, and probably 

 in both the products are further used in the animal economy in 

 the rebuilding of imaginal tissues. Sarcoplasm and nucleus are 

 both involved in this digestion, though the latter seems more 

 resistant to this agent of destruction and dark staining granules of 

 nuclear material are found late scattered through the body. In 

 connection with this it should be stated that other investigators 

 agree that not all sarcolytes or muscular debris are incorporated 

 in phagocytes. Bruyne ('98) says that many sarcolytes break 

 up without being acted upon by phagocytes. He quotes Loose 

 as giving statistical estimation that there are from 90 per cent, 

 to 96 per cent, free sarcolytes ; 4 per cent, to 6 per cent, sur- 

 rounded by a plasmic envelope, and that 3 per cent, may be 

 found in a plasmic area bearing a nucleus. 



In brief, in the process by which the larval muscles degenerate 

 and are destroyed, it has been found that the degeneration proper 

 is a chemical one unaided by any physical action by cells outside 



