A procedure is described for precise location of the capsula of a muscle spindle within the muscle by a restricted coagulation which abolishes the discharge of the spindle afferent. The point for coagulation was approximately determined by careful stretching of a little portion of muscle fibres, by slight pressure on the external and internal surface of the muscle, by intramuscular and external electric stimulation. The analysis of the dynamic and static sensitivity of 48 units shows that the differences in responses to stepwise stretching existing among both primary and secondary endings do not depend on the location of muscle spindles in different parts of m. soleus, but probably reflect variations in the density of afferent terminal contacts in 3 types of intrafusal muscle fibres.