bkeed: metamorphosis of the muscles of a beetle. 347 



such a meaning of the word, the presence of " Kornchenkugeln " in an 

 animal implies, as a necessary corollary, the breaking up of muscles into 

 fragments somewhere in the body, and the ingestion of these fragments 

 by the leucocytes. This corollary is probably not generally true in any 

 of the insects except the higher Diptera, and statements as to the 

 presence of typical "Kornchenkugeln" in other groups of insects must 

 be taken with reserve, unless some evidence is offered that they are 

 " Kornchenkugeln " and not leucocytes containing bodies derived from 

 some other source than degenerating muscles. According to this defini- 

 tion, " Kornchenkugeln " is not equivalent to " phagocyte," since it in- 

 cludes only a particular class of phagocytes, or, if Berlese's idea of the 

 function of the cells be correct, they ought not to be called phagocytes 

 at all. 



Another cause of confusion is found in statements that muscles de- 

 generate when, from later observations, it is evident that metamorphose 

 or some equivalent word is intended. In the present paper, whenever it 

 is stated that a muscle degenerates, the meaning is that no part of its 

 substance retains its morphological integrity to function as part of a 

 muscle or as any other tissue. By metamorphosis of muscles is signified 

 that some part, or all, of the muscle substance persists, with more or 

 less change in structure, and functions in the adult either as muscular 

 tissue or — if Berlese's idea in regard to the development of the imaginal 

 fat body in Muscidae be correct — sometimes as fat tissue. 



B. Observatioxs. 



1. Methods. 



Serial sections of either the entire insect, or of a large part of its body, 

 were used, in order that any particular muscle might be identified. 

 Nearly all of the usually recommended fixing fluids were tried. The 

 best results were obtained by killing in hot (70° C.) water and fixing 

 in a cold, saturated solution of corrosive sublimate in 35% alcohol, 

 or in cold picro-sulphuric acid. It is necessary to cut the animal 

 open, in order to allow the fixing fluids to penetrate. Objects were 

 left in the fixing fluids for several hours, even as long as twenty- 

 four hours in many cases. Hermann's platino-aceto-osmic and Flem- 

 ming's chromo-aceto-osmic mixtures are good for special purposes, but, 

 on account of their lack of penetrating power, they are not as good for 

 general results. 



VOL. XL. — NO. 7 8 



