Abstract
Ligation of the cardiac-recurrent nerve in adult females of Calliphora resulted in an accumulation of secretory material in the proximal part of the nerve. The secretory material was demonstrated partly in stained sections, partly in living nerves by means of darkfield illumination. By the latter method moniliform bluish white nerve fibres could be seen in the living normal (i.e. unligated) cardiac-recurrent nerve. In all probability this appearance of the nerve fibres is due to their content of neurosecretory material. Some axons of the nervi oesophagei and the nervi corporis allati had a similar appearance. No such fibres could be observed in the living abdominal nerve, and ligation of this nerve did not result in an accumulation of secretory material.