Also for , the neutral gas is mostly in the H phase. I is underabundant in the inner 6kpc and cannot be accounted for by photodissociation of H by H II regions. Asymmetry in the observed molecular gas distribution and kinematics of M100 seems related with the three-arm structure studied by Elmegreen and collaborators. Overlaid on gray scale images of I and I . Isovelocities go from 1450kms to 1750kms by steps of .
Thick contours stand for the systemic velocity .