OCTOPUS ARM, REGENERATION AND STRUCTURE 23 
take place simultaneously; at any rate, they alter their form, 
appearing round instead of elongated. These two processes 
continue until the nucleus has the appearance of a solid mass 
of chromatin. Then it breaks up into two, sometimes three 
parts, a process which has been called fragmentation (fig. 28). 
These nuclear fragments probably have great qualities of resist- 
ance, for they endure the whole process of degeneration, are 
present in its very first stage, and are still visible when the 
tissue has become quite necrotic. I was not able to find any 
phagocytic formations consisting of sarcoplasm and parts of 
the nucleus, such as Metchnikoff (’92) discovered in the degen- 
erating muscles of vertebrates. Neither was I able to detect 
a fatty degeneration which Bordage (’14) found to be the case 
in the muscles of Orthoptera. 
Soon after the wound has been covered by blood, corpuscles 
from the blood-clot migrate into the degenerated muscles and 
begin to dissolve and absorb the disintegrated parts. The 
cloddy remnants of the muscles, which up to the appearance 
of the blood-corpuscles, consisted of a solid mass, begin to dis- 
integrate, and at the same time the nuclear fragments (described 
above) decrease in number (fig. 29). Finally so many blood- 
corpuscles collect in the degenerated muscle tissue that the 
latter appears like the primary blastema and is hardly to be 
distinguished from it. 
The first sign of regeneration in the muscle tissues is the ap- 
pearance of large cells, which have very little protoplasm and 
seem to consist only of a large nucleus (fig. 30). These cells 
first appear in that part of the blastema which occupies the place 
formerly filled by the degenerated muscles. These cells are 
most probably sarcoblasts, and like the sarcoblasts of the verte- 
brates originate in the old muscle tissue. It is difficult to give 
any exact information as to how they are formed or as to whether 
the whole muscle fiber or only a part (and which part) contributes 
the necessary material. But there can be no doubt about their 
actually being sarcoblasts, for their development into muscle 
fibers can easily be followed up in later stages. The sarcoblasts 
have a rounded or oval nucleus containing very fine granules 
