Slow flow was followed in unmyelinated olfactory axons, severed from their cell bodies, at 14 degrees C, 21 degrees C, and 31 degrees C. Slow flow does not stop after axotomy but rather accelerates to a value 3.3 times faster than the rates measured in an intact nerve. These velocities are equivalent to the rates of slow flow characteristic of regenerating fibers. The injury appears to have an influence on the contralateral intact nerve, where slow flow velocity increases to severed nerve values for several days before reverting to intact nerve rates. It can be hypothesized that the increase in the rate of slow flow is triggered by a factor repressed in intact nerve but released into the blood stream following injury.