Comment on: "Transverse-Mass $M_\perp$ Dependence of Dilepton Emission   from Preequilibrium and Quark-Gluon Plasma in High Energy Nucleus-Nucleus   Collisions"
  In a recent Letter, Geiger presents calculations of the dilepton emission from the early stage of ultrarelativistic heavy ion collisions using the parton cascade model (PCM). He shows that the $M_\perp$ scaling is not observed. In this Comment, we point out that this is largely due to a defect in the PCM. 
M. Asakawa