How do I select all nodes in a selected area in Inkscape?

I want to be able to copy a vectorized picture of a T lymphocyte in this file (http://ift.tt/1zyHe3S), including all of its nodes but whenever I try and copy it (via clicking on all visible nodes using the "Edit paths by nodes" tool, into a new Inkscape document it copies it as a raster image that's very pixelated. Any idea of how I can better copy the vectorized image?