  The Hamiltonian describing Matrix theory on T^n is identified with the
Hamiltonian describing the dynamics of D0-branes on T^n in an appropriate weak
coupling limit for all n up to 5. New subtleties arise in taking this weak
coupling limit for n=6, since the transverse size of the D0 brane system blows
up in this limit. This can be attributed to the appearance of extra light
states in the theory from wrapped D6 branes. This subtlety is related to the
difficulty in finding a Matrix formulation of M-theory on T^6.
