The subject of the report is a nebula in OUR galaxy.

The comment "Most nebulae are either spiral galaxies ...." is both irrelevant and incorrect when written anytime after the early 1900s.

The nebula is OUR galaxy is NOT a galaxy and most nebula, in fact ALL nebula, are mixtures of gas and dust. They have nothing whatsoever to do with galaxies other than that they exist within one.

DA Morgan