OCTOPUS ARM, REGENERATION AND STRUCTURE 33 
inactive for the first few hours after operation. Later on the 
epithelium cells at the edge of the wound grow flat, the nuclei 
which up to that time were vertical change their position, be- 
coming parallel to the edge of the wound. ‘The flat cells creep 
over the wound from all sides, till the latter is completely covered 
by a very thin tessellated epithelium, provided with a cuticle. 
The tessellated epithelium gradually becomes cubical and later 
on cylindrical. 
2. The musculature. Disintegration begins in the musculature 
soon after operation. The sarcoplasm degenerates. The spiral 
fibers expand, thus filling the gaps left by the sarcoplasm, and 
at the same time narrowing the central duct and crowding out 
the granulated substance of the core. The result of this degen- 
eration is a cloddy mass, which shows less affinity to staining 
agents than the normal muscle fiber. ‘The nuclei become homo- 
geneous globules of chromatin, and break up into two or three 
pieces (fragmentation). The degenerated muscles are partly 
dissolved or absorbed by blood-corpuscles which migrate into 
the disintegrated tissue. The muscles regenerate by means of 
-sarcoblasts. The sarcoblast possesses quite a large nucleus, 
which is provided with one nucleolus. The sarcoblasts later 
migrate to the distal part of the stump, and in combination with 
the neuroblasts form the second blastema. They multiply by 
means of indirect or mitotic division. The sarcoblasts of the 
external longitudinal muscles are the first to exhibit muscle 
fibers. In the transverse muscles fibers appear at a much later 
date. The muscles of the suckers are evolved from lateral 
proliferations of the sareoblasts of the central muscle-fiber 
bundle. 
3. The nervous system. The first sign of disintegration of the 
axial nerve is found in the layer of ganglion cells. The ectoplasm 
of these cells degenerates and the nucleus shrinks, the chromatin 
gathering around the nucleolus. The nuclei of the neuroglia 
undergo the same change. The fibers of the myelin cords expand 
and often grow five times the size of the normal tissue. The 
only signs of degeneration visible in the neuropil are the shrinking 
of the neuroglia nuclei embedded there and a decrease of its 
