At this time, we didnt even know that there are galaxies out there! What we know was that apart from our sun and planets, there are millions of stars everywhere and many nebula, which were considered as gaseous clouds. Even the best telescopes of the time couldnt reveal that many of the gaseous clouds were infect group of stars galaxies contains million of stars. It is very surprising to me that while formulating General Theory of Relativity, Einstein didnt knew about the structure of the universe.
Although a debate was going on among the scientists that some of the gaseous clouds are composed of stars and they themselves are altogether a separate system, galaxy only was to prove this was to actually see stars in any of the cloud, but, telescopes still were not that powerful.
In the year 1917, Heber Curtis and George Ritchey announced that they have found novae in the Andromedo Spiral (a gaseous cloud). Novae event basically are connected to life cycle of stars, when a star dies, it becomes tremendously bright and stays in that way for many ways. Sometimes they become so bright that they could be even seen at day time. Such a novae was spotted in the Andromedo Spiral, which directly means that Andromedo Spiral is a system of stars. But it took long to settle the doubt. In 1922, Ernst opik deduces that Andromedo