OCTOPUS ARM, REGENERATION AND STRUCTURE jl 
possible that the ganglia arise in the embryonic connective tissue 
under the influence of the growing nerve. In a piece which 
had been fixed three or four days after operation and which was 
just on the point of beginning regeneration, I was able to observe 
fine fibers of the peripheral nerves, which originated in the 
uninjured part of the axial nerve, but innervated one of the 
amputated suckers growing into the primary blastema. At the 
distal end of one of these fine fibers I could detect some cells 
which showed a marked similarity to the nerve cells (fig. 39).° 
The subcutaneous connective tissue is most probably evolved 
from the primary blastema. At first, however, the latter is 
separated from the subjacent connective tissue by a sharp 
boundary line, which later on disappears. Unfortunately, I am 
not able to give any detailed account of the regeneration of the 
vascular system. I heard that Minervini had studied this 
process, but I was not able to find his publication. Authors 
who have studied the regeneration of the vascular system in 
other animals claim that the new blood-vessels are formed by 
a proliferation of the endothelium of the old blood-vessels. I 
was not able to detect any proliferation of endothelium in the 
regenerating arm of the Cephalopoda. The main artery and 
the veins grow rapidly and are visible in the most distal portion 
of the regenerated piece. In such a stage as is exhibited in 
figure 8 the blood-vessels form a kind of plexus which is well 
filled with blood. 
I did not make the regeneration of the epithelial glands and 
the chromatophores the subject of any closer study. Chun 
has published a very detailed account of the development of 
the chromatophores. 
SUMMARY 
The most important morphological changes which occur during 
the regeneration of the arm of the Cephalopoda (Octopus vul- 
garis) are the following: 
1. Wound healing. After operation the edges of the wound 
curl inward. The axial nerve protrudes beyond the other tissues. 
Bleeding does not take place immediately after operation, but 
