HISTOI , OGICAL AND HISTOCHEMICAt OBSERVATIONS OF THE CEPHAUC NEUROSECRETORY SYSTEM THE CRAB , PARAGRAPSUS

Anatomical, cytological and histochemical features of the neurosecretory system of the crab, l'aragrapsus gaimardii are described, In the brain and· the commissural ganglia, three types of neurosecretory cells are distinguished, The distribution of these cells in the brain and the commissural ganglia is described. In the eyestalk, four types of neurosecretory cells are identified and the distribution of these cells is described. The neurosecretory cells of the brain, the commissural ganglia, and of the eyes talks are all paraJdehyde fuchsin positive (PFpositive), Their tinctorial properties with the chrome, haematoxylin phloxine technique are described. The neurohaemaJ organ 'Of the eyestalk, the sinus gland, is described both as regards its anatomical characters and its staining properties. The presence 'Of all'Ochthon'Ous cells in the sinus gland is revealed, The allochthonous neuroglial cells of the sinus gland do not appear t'O be active gli'Osecret'Ory cells, However, some 'Of the neur'Oglial cells of the brain, especially th'Ose 'Of the protocerebrum, do appear t'O be active gli'Osecretory cells. The neurosecretory material of the cephalic neurosecret'Ory system of P. gaimardii is pr'Oteinace'Ous with disulphide groups being markedly present