408 



represented not by the loose individual fibrils, but bv a 

 number of loose bundles, each consisting of a few fibrillae 

 which have become fused together. 

 f^ Having removed the more palatable interstitial substance 



) the leucocytes now turn their attention to the fibrillae. The 

 process of destruction seems to be much more difficult here. 

 I The leucocytes apply themselves round a piece of the fibril, 

 and several such leucocytes may often be seen,' arranged side 

 by side along a single fibrilla in their attempt to destroy it. 

 The process is actively going on in the fresh pupa, and six 

 hours later the fibrillae have entirely vanished. Muscular 

 regeneration often occurs in connection with these degen- 

 erating fibres and will be referred to below. 



The histolytic action of the phagocytes on the muscles 

 was first discovered independently by van Rees (1884), and 

 by Kowalevsky (1885), using Calliphora as material. 

 Korotneff (1892), on the other hand, could not observe it 

 in the moth Tinea, but his observations were made on the 

 thoracic muscles. He regarded these, apparently erroneously, 

 as arising by regeneration of the larval muscles. Berlese's 

 conclusions have already been referred to earlier. 



In Calliphora Perez finds that the leucocytes generally 

 enter the muscles, and break off small pieces of muscle. This 

 muscle has not undergone any visible degeneration ; even 

 within the leucocytes it seems to retain its structure for a 

 ' considerable period. In Nasonia the degeneration of muscles 

 preceding the phagocytosis invariably occurs, and all stages 

 of disorganization from muscles which have merely lost or 

 even only incompletely lost their striations, to others which 

 have undergone total granular degeneration, may be observed. 



The Regeneration of the Muscular System. 



An examination of the process of regeneration of the 

 muscular system revealed the remarkable fact that a con- 

 siderable difference exists in the actual morphology of the 

 various muscles of the adult wasp; the muscles of the legs, 

 ovipositor, and mouth appendages have similar methods of 

 development, and though the mature surface abdominal 

 muscles are similar to these, their mode of development is 

 quite different. A single pharyngeal dilator muscle, on the 

 other hand, corresponds not to a single leg muscle, but to a 

 whole group of them; while the great thoracic muscles (wing 

 muscles) are quite unique in that they are composed of a 

 great many muscle fibres, all running parallel to one another, 

 ' and quite devoid of fibrillae. These remarks will become 

 clearer when we have considered the development of the 

 various muscles ; it is enough to say here that failure to 



