405 



appear otherwise quite normal, and are still capable of func- 

 tioning, though only very feebly. (The shedding of the last 

 larval cuticle is itself brought about by muscular movements 

 of the abdomen.) 



Shortly after moulting, however, the muscles lose their 

 striations, the substance of the striations spreading itself 

 uniformly through the fibrils (the substance of the fibrils 

 becoming, in consequence, uniformly heavily staining (fig. 

 107). 



The nucleus meanwhile undergoes certain changes; the 

 chromatic material of the nucleus may change from a rough 

 granulation to a fine chromatic dust, the particles of which 

 may be clumped together (fig. 107). This dust may be forced 

 into the cytoplasm. It may even scatter itself through the 

 substance of the muscle, leaving only the empty nuclear mem- 

 brane behind. This occurs in certain of the dorsal abdominal 

 muscles whose further disappearance is intimately related with 

 developing myoblasts, and is rendered possible by the degen- 

 eration of the fibrillae into a loose granular fluid. 



At other times, however, the nuclei remain, to external 

 appearances, normal, except for the presence of the great 

 nucleolus. 



At about the sixth hour after pupation those muscles 

 whjch have not become penetrated by the myoblasts of devel- j 

 oping imaginal muscles (see below) are f allien upon by 

 leucocytes (fig. 105). 



The leucocytes begin to cluster around the dead muscle 

 fibres and the muscles are rapidly absorbed. Perez has ex- 

 amined the process fully in Calliphora, and I shall describe it 

 only briefly here, referring mainly to the points of difference as 

 seen in the two insects. v — . . 



When the leucocyte has approached" close to the degen- 

 erated muscle it pushes out a pseudopod which appears tq 

 dissolve its way through the still unbroken saroolemma.| y 0^ ' 

 Within the musclei^^ gradually swells out and drags a certain; ' ' 



amount of the leucocyte after it; so far as I could observe, it 

 does not entirely enter the fibre (fig. 129). ; 



The actual penetration of the leucocyte into the muscles^] 

 occurs infrequently. Much more often the leucocytes con- 

 tent themselves with clustering around the sarcolemma where 

 it has been ruptured by the more adventurous ones, dissolving 

 off small pieces there, which accumulate within the leucocytes, 

 in the form of large granules. __^ 



Occasionaly, however, a much more voracious leucocyte 

 may engulf long strips of muscle substance; so long, indeed, 

 may the strips be, that it becomes necessary to bend them 

 about to accommodate them within the body of the corpuscle ; 



