MUSCULATURE OF CULEX PUNGENS. 293 



Fig. 4, and Plate XL, Fig. I, besides showing the conditions 

 above described, present several small cells in the granular 

 material about the muscle lying free with the nuclei. They are 

 probably the first appearance of phagocytes, and in this instance, 

 it will be noted, they have entered before the fibers have lost 

 their striations. If one examines the former figure the origin of 

 these cells becomes plainly evident. In the sheath surrounding 

 the bundle are several small elongated cells. Some of these 

 appear large and more spherical, and show by their position and 

 morphological characteristics, their relation to the spherical ones 

 within the sheath though cell division has not been observed. 

 It seems very probable that the phagocytes of Oilc.v are derived, 

 not from the blood or myoclasts of Bruyne, but from special 

 mesodermic cells which arise by a proliferation of the cells exist- 

 ing in the body tissues. These cells are later found much larger 

 because of the detritus which they have incorporated, and pass 

 into the body cavity where we shall examine them more carefully 

 a little later. 



Of the authors who do not attribute to phagocytosis the initial 

 cause of muscular degeneration, Korotneff ('92) and Bataillon 

 ('90) describe phagocytes as playing a secondary part in the 

 destruction of the debris as described in Cnlex. Breed ('03) says 

 that there may be such a condition but does not note it in his 

 work, while Needham ('oo) claims the total absence of phagocytes 

 until the imaginal stage. Breed says the degeneration of the 

 larval muscles is entirely chemical, there being no evidence of 

 phagocytosis. The tracheal cells which he describes, and their 

 ultimate function is quite comparable to the phagocytes above 

 described in Cnlc.v. In the one the cells are derived from 

 preexisting cells in the tracheoles and in the other from preexist- 

 ing cells in the connective tissue. Both the tracheal cells and 

 the connective tissue cells are of mesodermic origin not specialized 

 to particular functions, and just such cells as one would expect 

 would give rise to phagocytic cells. Again one may find anal- 

 ogous cases in pathology. In the study of inflammatory changes 

 in various tissues a proliferation and phagocytosis is very often 

 observed. The cells which become phagocytic are derived in most 

 instances from either connective-tissue cells or endothelial cells. 



