20 MATHILDE M. LANGE 
When a short distal piece is amputated, very little blood leaves 
the blood-vessels. In such regenerations there is little primary 
blastema (fig. 23). 
In his study of the regeneration in Gastropoda, Techow 
describes processes very similar to those which I have just de- 
picted in Cephalopoda. He found that the wound remains open 
without any covering whatever during the first few hours after 
operation. Then the blood-vessels leading to the wound become 
filled with cells, which later form a layer over the wound. Te- 
chow gave a detailed description of these cells, but did not classify 
them histologically. In my opinion, these are haemolymph 
cells, for it would be rather strange for the blood-vessels to be 
suddenly filled with a great number of cells which normally 
did not belong there. An appearance of strange cells in the 
blood-vessels would denote a pathological condition. But these 
cells later on form a blastemal tissue, so they cannot be path- 
ological. These cells cannot be anything else than blood-cor- 
puscles, and from Techow’s paper we can clearly see that Gas- 
tropoda, like the Cephalopoda, do not bleed immediately after 
operation, but only after a period of several hours has elapsed. 
During the formation of the cicatricial tissue, which acts as 
a preliminary covering for the wound, the epithelium which is 
destined to form the final covering remains inactive. It is diffi- 
cult to state just how much time must elapse after operation 
before the regeneration of the epithelium is initiated. It varies 
from ten hours to two days. The causes of this fluctuation are 
probably the same as already mentioned on page 9. Before 
the epithelium begins to stretch over the wound, the basal 
membrane of the uninjured epithelial cells immediately adjacent 
to the wound draws back a little. According to Hescheler, 
the same thing happens before the regeneration of the epithelium 
in Lumbricidae. The cells from which the basal membrane 
has withdrawn are no longer in such close connection with the 
more proximal epithelial cells, and probably on that account 
able to aiter their form. They become flat, and their nuclei, 
which formerly were vertical, are now in horizontal position. 
Figure 24 shows a picture of such horizontal nuclei. These 
