sode rather than 
continuant-part). They could be applied to a much broader universe of 
mereosums which would include things like 'the accumulated stuff in 
any set of pieces of space', or they could be restricted to sets 
consisting of countable sums of spheres in n-space. If collections 
are identified with mereosums, as Chris P and Nicola urge, they could 
be applied to collections (with some care), but if not then not. They 
might or might not be taken to include surfaces as parts (I earlier 
thought t