368 BULLETIN: MUSEUM OF COMPARA.TIVE ZOOLOGY. 



rarely possible to confirm the results of another investigator's work more 

 completely than Rengel's results have been confirmed by my own 

 investigation. 



The results of De Bruyne's ('97) investigation of Tenebrio may be 

 entirely disregarded, because there can be little doubt but that he has 

 mistaken tlie fundamental nature of the changes with which he was 

 dealing. Misled by the similarity in appearance of cross sections of 

 metamorphosing muscles (such as my Figure 15, Plate 6) to cross sec- 

 tions of the degenerating muscles of Muscidae (see figures given by 

 Kowalevsky, '87, Van Rees, '88, and others), he has concluded that the 

 muscles in Tenebrio likewise degenerate. As a matter of fact, there can 

 be no doubt but that he was dealing with metamorphosing muscles 

 which retained their individuality thoughout pupal life, as is indicated by 

 Kriiger's ('98) results on the same insect, as well as by the present study 

 of Coleopterous forms. The probability is that his leucocytes, which 

 he found engulfing fragments of muscle, are the same as the tracheal cells 

 of the present paper, and that his " Kornchenkugeln " are the same as 

 the detached fat cells described by Kriiger ('98, p. 16). 



Kriiger ('98) was venturesome in generalizing from such meagre data, 

 but his conclusion is entirely confirmed by the present research. All of 

 the imaginal wing muscles are metarnorphosed larval muscles, though 

 some of the other metathoracic muscles nearby are not. However, it is 

 questionable if the cells which Kriiger ('98, p. 1 7) describes as " "Weis- 

 mannsche Kornchenzellen " are such in reality. He has given us no 

 evidence to support the view that the inclusions in these cells are 

 muscle fragments. Other, just as probable, explanations of the nature 

 of these cells might be given. 



Karawaiew's statement ('99, p. 202), that he finds no phagocytosis 

 of the muscles of Anobium, agrees with what has been found in 

 Thymalus. 



It was impossible to explain the disagreement of Berlese's results with 

 the results of the present research, until a copy of his last paper (:02'') 

 was received. His idea, that there is, in the metamorphosis of the 

 muscles of all the metabolic insects : first, an emigration of nuclei from 

 the larval muscles ; secondly, a formation of " sarcocytes " from these ; 

 thirdly, a transformation of these " sarcocytes " into " myocytes ; " and, 

 finally, a production of new muscles from these, meets a fatal objection, 

 as far as Coleoptera are concerned, when the anatomical changes of 

 these muscles are considered. The first half of my paper is taken up 

 with tracing individual larval muscles in their metamorphosis into 



