BREED: 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 
‘“‘Koérnchenkugeln” and not leucocytes containing bodies derived from 
some other source than degenerating muscles. According to this defini- 
tion, “ Kérnchenkugeln” 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 isintended. 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. OBSERVATIONS, 
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 
