Comparison of measured spiral arm properties with model predictions

We present measurements of the morphological properties of the spiral arms in a sample of 17 galaxies for which density wave and stochastic theory predictions are available. For both models crude correlations of predicted and observed arm properties are apparent along the Hubble sequence. In detail, however, the agreement is poor for both models. Arm pitch and arm widths are at least as well correlated with the rotational velocities of the galaxies, independent of the model. This sugggests that the trends in spiral structure observed along the Hubble sequence may be largely kinematic in origin