5 
OCTOPUS ARM, REGENERATION AND STRUCTURE 2 
to Techow, however, this rule is not applicable to the muscles 
of the Gastropoda. He claims that in the course of regeneration 
the new muscles are also evolved from large cells (sarcoblasts), 
but believes that these cells are originally epithelial cells which 
have migrated into the subjacent tissue. There are very few 
reports on the histological processes connected with the muscle 
regeneration in Mollusca. I could only find three in all—Te- 
chow’s, Hanko’s, and the paper published by Cucagna and Nus- 
baum on the regeneration in Nudibranchia. Techow’s opinion 
on the subject has already been given. Hanko claims that 
the new muscles are a product of the old, but he does not mention 
the presence of any sarcoblasts. He states that certain cells 
(Wanderzellen), whose origin he does not explain, gather around 
the distal and somewhat inflated end of the muscle stump. These 
cells form a kind of bridge between the muscle stump and epi- 
thelium, and along this bridge the new muscle fibers, which are 
formed by proliferations of the old, develop. According to 
Cucagna and Nusbaum, the new muscles are evolved from 
sareocytes (sarcoblasts) formed of the sarcoplasm and nucleus 
of the old muscles. Schultz, Bordage (14) and Friedrich state 
that the same is true of the muscles of the Arthropoda. 
Barfurth (91), Nauwerk (’90), and Fraisse (’86) found that 
the muscles of the vertebrates also regenerate by means of 
sarcoblasts. 
The musculature of the suckers is formed by lateral pro- 
liferations of the central muscle bundle (fig. 33). These buds 
are soon separated from their seat of origin by connective tissue. 
The invagination of external tissue which causes the formation 
of the sucking cavity also indents the muscle-bud, consisting 
of sarcoblasts. In the course of further development the sarco- 
blasts are grouped around the cavity in two distinct parallel 
layers (fig. 34). Later these sarcoblasts develop into the radi- 
ating and circular muscles of the sucker. As in the transverse 
muscles, the formation of the final muscle fibers begins later in 
the sucker muscles than in the longitudinal muscles of the 
central muscle bundle. 
