The correct spin direction of the Galaxy.
In the theory about the development of Spiral-Galaxies it is explained, how it comes to this spin direction and to the generation of a branch at the outside of the mainstream of a Galaxy-Arm.

At the outside of the Galaxy NGC4594 you can recognize a circulating band of "dark material". In the Theory about the development of Spiral-Galaxies it is explained, where this "dark material" was generated and how did this material move to the outer edge of Spiral-Galaxy.

Two contrary turning Spiral-Galaxies are collided.
In the Theory about the development of Spiral-Galaxies, it is explained, whereby it comes to that collision.

The generation of a Barred-Spiral-Galaxy, as well as a great mass of Dark-Material at the outer edge of a Spiral-Galaxy could not be explained by the Black-Hole-Theory.