950 THE AMERICAN NATURALIST.  [VoL. XXXIII. 
something more than this. When I recall how similar in form 
the small medusæ are, coming as they may from pieces of very 
different shapes, I am inclined to believe that there is some- 
thing more in the process than only the fusion of the cut edges, 
and that the piece does in reality mould itself into the medusa- 
form, as Hargitt pointed out. 
The further question suggests itself for consideration: Is 
the process by which the edges bend in and ultimately fuse 
simply a mechanical result depending upon the tensions set in 
play when part is cut off? I think not, at least not entirely. 
The bending takes place very slowly, and not quickly, as would 
be the case were it simply a roughly mechanical process. The 
form of the piece continues to change even after the edges 
have met and fused, pointing, I think, to the conclusion that 
the entire process is one of rounding up of the piece in the 
direction of least resistance. 
The meeting of the edges may sometimes be due simply 
to an accidental meeting of the bent-in portions, but gener- 
ally the process is a more orderly one, and of such a sort that 
it seems to be correlated with the process of remoulding. The 
fact that the cut edges always succeed in finding each other, 
even in very unsymmetrical pieces, shows that something more 
than a gross physical process is at work. 
If we attempt to analyze the process so far as is possible 
at present, we can, I think, make out the following factors. 
The bending in, taking place in the piece as a whole, seems to 
be the result of active changes in the living tissues. This 
leads to the piece assuming more and more the typical form. 
The meeting of the edges may be due sometimes to accidental 
contact resulting from the bending in of the piece, but more 
often the closing of the cut surface is due to a sequence of 
well-defined events. At some point where two cut edges’ make 
an angle with each other they begin to draw together at the 
angle. The process proceeds from this point until, step by 
step, the complete fusion is brought about. It is as though, 
first at the angle, the parts that are continuous around the 
angle draw together, and the edges coming together fuse. 
Then new parts that are brought up to the new angle repeat 
