Our main goal is to review: 1) some physical mechanisms which form the observed structures in galactic disks; 2) the discovery of new galactic structures predicted earlier. Specifically in the first part of the paper we discuss some questions associated with spiral structure. The second part is devoted to the prediction and discovery of giant

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New ground based observing opportunities are becoming, or about to become, available to astronomers for QSO research. These, combined with state of the art focal plane instruments, provide unprecedented sensitivity for detecting faint surface brightness features. During the talk I will take the liberty of talking about one of these new large

We present a kinematical comparison of the HI and HII contents of the barred spiral galaxy NGC 3359. Non-circular motions are observed near the strong bar and the spiral arms of the galaxy as seen in the moment one and residual velocity field maps.

We analyze the observed properties of nested and single stellar bar systems in disk galaxies. Our sample consists of 56 Seyfert and 56 non-Seyfert galaxies. We use HST H-band images of the central parts and ground-based images of the outer parts with ellipse fitting to find bars. Our main result is a clear division between the secondary and primary

We are studying the properties of a sample of satellite galaxies around nearby isolated spirals (Zaritsky et al. 1997), with the aim of testing hierarchical models of galaxy formation. Satellite galaxies can give us information on intermediate steps in the merging and aggregation processes which, according to the models, form the larger dynamical