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BREED: METAMORPHOSIS OF THE MUSCLES OF A BEETLE. 367 
forms has interpreted entirely correctly the phemomena which he has 
seen. I affirm this the more confidently because in the controversy 
which has arisen among these authors neither side has satisfactorily 
explained the observations of the other. They all agree in describing 
phenomena which are so like those of which I have here given an 
account for Coleoptera, that it does not seem possible that there should 
be any fundamental differences between the two groups. It is evident, 
chiefly from the completed paper of Anglas (:01), that there is in 
Hymenoptera a metamorphosis of most of the larval muscles, a degener- 
ation of the remaining ones, and a new formation in the pupa of some 
imaginal muscles. There are no persistent larval muscles such as exist 
in Coleoptera, Lepidoptera, and orthorraphic Diptera, the abdominal 
muscles undergoing a less complete metamorphosis than the metamor- 
phosing muscles of the remainder of the body. 
The settlement of the whole controversy between the five authors 
(Karawaiew, Terre, Anglas, Pérez, Berlese) depends on the interpreta- 
tion of the nature of certain cells found in the regions of the metamor- 
phosing and degenerating muscles, these cells being apparently exactly 
comparable to the cells in Coleoptera which have been spoken of in the 
present paper as tracheal cells. None of the five authors mentioned 
above has considered the possibility of the tracheal nature of these cells. 
Nevertheless, none of their observations preclude such an _ origin. 
Karawaiew, Terre, and Berlese contend that these cells are not leuco- 
cytes, but are developed from the nuclei of the larval muscles ; whereas 
Anglas and Pérez contend that they are not developed from the nuclei of 
the larval muscles, but are leucocytes. Is it not possible that both sides 
are correct in their negative conclusions and incorrect in their positive 
affirmations? May not these cells be developed from the tracheoles of 
the larval muscles, instead of from either of the tissues mentioned ? 
None of these investigators has described the origin of the tracheae of 
the imaginal muscles. Yet these tracheae are so exceedingly abundant 
ia the region of the wing muscles, that their origin cannot be so incon- 
spicuous as to have been overlooked entirely, nor ought it to have been 
neglected, as it has been. It is to be hoped that some of these authors 
will at least consider the possibility of the explanation which I have 
suggested, since, if correct, it will straighten out what otherwise is an 
apparently hopeless controversy. 
We will now consider the researches on Coleoptera. <A review of the 
disagreements of Rengel (’96) and Deegener (:00) has already been 
given in considering the changes of the intestinal musculature. It is 
