From published catalogs, basic physical properties including diameters, masses, and neutral hydrogen contents of spiral galaxies have been studied as a function of the arm class. The results indicate that galaxies with well-defined arms have longer scale-lengths (a difference comparable in the red to that in the blue) and are more massive (in both the stellar and gaseous components) than the galaxies of more flocculent form, but that these parameters are so scaled that the combined mass surface density of stars and gas does not vary significantly with arm class. While postulating that the increased mass is associated with the formation of well-defined arms, independently of morphological class, the continuing need for arm-interarm comparisons of star-formation efficiency to elucidate mechanisms on galaxy-wide scales is stressed.