OCTOPUS ARM, REGENERATION AND STRUCTURE 15 
contains some blood in its most distal portion, most of which 
consists chiefly of blood-corpuscles without plasma. Cuénot 
claims that such blood-corpuscles are degenerated. All the 
blood-vessels leading toward the wound contain very little blood, 
nor is there any trace of blood on the wound itself. I believe 
that up to the time at which this piece had been fixed, no bleeding 
had yet taken place. The reasons which led me to have this 
opinion have been discussed in the previous chapter (p. 8). 
Young stages of regeneration (such as are shown in fig. 17) are 
always open, no covering or closing of the wound having yet 
taken place. 
Techow (10) found that the wounds of the gastropods were 
provisionally closed by a clot which was formed by the contents 
of the blood-vessels. I found that the wounds of the Cephalo- 
poda were closed in the same manner. About five or six hours 
after operation all blood-vessels leading to the wound are filled 
with blood, which after leaving the vessels spreads over the 
wound, thus forming a protective covering for the same. Atten- 
tion has already been drawn to the fact that the blood of the 
Cephalopoda contains no fibrinogen (p. 5), therefore the clot 
which preliminarily closes the wound cannot be formed through 
blood coagulation, as is the case in wounds of vertebrates and 
arthropods. The wound can only be closed by the agglu- 
tination of the blood-corpuscles, and a histological study of the 
sections proved this to be the case. In agglutinating the blood- 
corpuscles form a kind of network (figs. 19, 20, and 21). In 
many other invertebrate animals the wounds are also closed 
by means of blood- or lymph-corpuscles. Techow (710), Hanko 
(’13),4 Cucagna (’15), and Nusbaum (’15) found it so for the 
Mollusca. Hescheler (’98), Nusbaum, and Friedlander (’95) 
claim that wounds of worms are closed in the same manner. 
Ost (’06), Friedrich (’06), and Reed (’05), who have studied the 
regeneration in Arthropoda, found that the wounds of these 
4Hanko studied the regeneration of Nassa mutabilis and speaks of blood 
coagulation as a means of closing the wound. This is probably an erroneous 
statement, for, according to Kollman, the blood of the gastropodes contains no 
fibrinogen, therefore coagulation is not possible. 
