28 
Journal of Agricultural Research 
Vol. XXVIII, No. 1 
clear plasma of the lacunae, and finally given off at the dissolving edge of the latter 
into the blood. 
The different kinds of bodies given off from the edge of a dissolving muscle 
are shown enlarged at B in figure 8. Here are seen free sarcolytes (a), a caryo- 
lyte ( d), and free muscle nuclei (c, c). It is to be noted, however, that the major¬ 
ity of the sarcolytes are given off in small globular masses (b, b ) which are ex¬ 
truded from the muscle, apparently in a thin matrix of plasma. These bodies 
soon become spherical (C) and are very suggestive of the Kornchenkugeln or 
spherules of granules of other writers. 
A “ Kornchenkugel ” is supposed to be a leucocyte or amoeboid blood cor¬ 
puscle gorged with the fragments of disintegrating larval muscles, which is to 
say, it is a phagocyte after a full meal. The term was first used in this sense by 
Weismann (58), but the idea has given rise to an endless discussion in the works 
of subsequent writers on insect metamorphosis. The present writer will not at¬ 
tempt to give a history of this subject here, since the reader will find in almost 
every other recent paper a good review of the results and conclusions of all 
other writers, and, if sufficiently interested, should consult the works of Weis¬ 
mann (58), Ganin (11), Metschnikoff (82), Van Rees (46, 47), Kowalevsky 
(24, 85), Rengel (48), Karawaiew (17), Needham (86), Anglas (1), Berlese 
(4, 5), Breed (10), P6rez (89), and other papers by these same and other writers 
which are listed in all bibliographies on insect metamorphosis. 
Some writers have believed that the leucocytes, either acting as phagocytes or 
by giving off some solvent (lyocytosis, Anglas, I), are the actual cause of the de¬ 
struction of the larval tissues when the latter reach a condition where their vital¬ 
ity is no longer sufficient to withstand the attacks of these ravenous or virulent 
cells. It has been shown by Berlese (4, 5), however, that even in the higher 
Diptera muscles are frequently to be seen in histolysis when the sarcolemma is 
yet intact and, therefore, before the leucocytes could attack their tissues. Be¬ 
sides this, it is well known that in many insects the metamorphosis of the tis¬ 
sues is not accompanied by phagocytosis. Karawaiew (17) says that phagocytes 
play a very unimportant part in the metamorphosis of the ant, while Korotneff 
(21) claims that there is a complete absence of phagocytosis in Tinea, and Rengel 
(48), Needham (86), and Breed (10) report the same for various beetles. 
Even in the Diptera the presence of phagocytes is not universal. Miall and 
Hammond (84) say that they “have never seen in Chironomus larval muscles 
excavated by phagocytes, nor fragments of striped muscles lying inside phago¬ 
cytes, though both can be demonstrated in the blow fly. In Chironomus the 
disintegration of the larval organs of the thorax is relatively slow, and the mus¬ 
cles, for instance, seem to waste gradually and uniformly while undergoing for a 
long time no marked change of external form.” Kellogg (18) has shown also 
that in Holorusia and in Blepharocera histolysis takes place without the occur¬ 
rence of phagocytosis, and Berlese (5) says the same of Mycetophila. Yet 
P6rez (89) still insists that, in the blow fly, phagocytosis is at least synchronous 
with histolysis, and he inclines to the belief that the attack of the leucocytes is 
the actual cause of the destruction of the muscles. Probably most investigators, 
however, now regard the leucocytes as mere scavengers that devour the products 
of histolysis, the latter resulting from some other unknown cause. Most writers 
believe that the phagocytes digest the engulfed particles and give the products 
back to the blood in a form that can be utilized by the growing tissues. Berlese, 
on the other hand, claims that they act as carriers only. 
Nearly all writers have admitted that, where the leucocytes play the part of 
phagocytes in the higher Diptera, they form the bodies known as “Kornchenku¬ 
geln” or “spherules of granules;” but Berlese has shown that similar bodies 
