24 W. BLAXLAND BENHAM. 
wound formed by the rupture, form a boundary to the portion 
separated as well as to the anterior region. The gonads are thus 
held in place, and do not project through the wound, and hence 
the rounded end of the body looks like the true anal end. During 
the above process the intestine has, of course, become nipped. 
After the epidermis has been ruptured one notices the 
surfaces of the wound to be covered with a flat epithelium 
(fig. 8, ep’). Whence comes this? Is it derived from the 
connective tissue? It looks as if the row of nuclei before 
mentioned had flattened out, and so given rise to the flat nuclei 
of this membrane. 
This appears to be the general history of the process of 
fission. But we are no nearer to the answer—how do the 
muscles become ruptured? why do they all give way at this 
particular plane? Further, is it merely a rupture of the 
fibrille, or is there a degeneration of these fibrillz over a cer- 
tain small area, viz. between the two rows of nuclei? Have 
these nuclei, or rather the cells belonging to these nuclei, any 
part to play in this rupture or degeneration, or are they merely 
a preparation for the new membrane which forms the ends of 
the fragments of the body ? 
At present I am unable to answer these questions with 
certainty. It appears to me, after a careful study of my pre- 
parations, that the muscle-fibrils do rupture; at any rate, if 
there is a degeneration of tissue, it occurs over only a very 
minute distance: the ends of the ruptured fibrils appear clean- 
cut (fig. 6), and I see no sign of any modification in their 
substance which would point to a degeneration. 
With regard to the second part of the query, viz. the action 
of the row of nuclei, I would suggest that they do play an 
active part in the process. The muscle-fibrils are wrapped 
together by connective tissue, which has the form of a network, 
through the meshes of which the fibrillz pass (fig. 9). At the 
point of future rupture this network is denser and the meshes 
smaller, and it may be that the cell-substance becomes actively 
contractile, and really nips the muscle-fibrils in two. On 
the other hand, we must not overlook the possibility of the 
