Unit spindle activity was recorded at dorsal roots of anesthetized cats to direct stimulation of efferent nerve. Early and late spindle discharges were studied in relation to extrafusal contractions. Calculated activation times showed many intrafusal times shorter than extrafusal. Some of the early spindles could be discharged reflexely by stimulation of the central end of ipsilateral nerves. A small group of these did not show any accompanying evidence of extrafusal contraction, supporting the general conclusion that a significant portion of early spindles are innervated and activated by a process fully as rapid as that in extrafusal muscle.