The Role of the Haemocytes in the Growth and Moulting of An Insect, Rhodnius Prolixus (Hemiptera)

ABSTRACT Growth and moulting in insects is initiated by a hormone produced in the neurosecretory cells of the brain. This brain factor activates the thoracic (or ‘prothoracic’) glands, which are then believed to secrete the definitive ‘growth and moulting hormone’. These conclusions are based chiefly on experiments with Rhodnius (Wigglesworth, 1940, 1952a), Lepidoptera (Fukuda, 1944; Williams, 1947), Diptera (Possompès, 1953) and Megaloptera (Rahm, 1952), and there is abundant histological and experimental evidence from other groups which points in the same direction (see Wigglesworth, 1954). The possibility remains, however, that there may be yet further links in the chain of endocrine organs, located, for example, in the abdomen. The object of the present work was to investigate this possibility in Rhodnius.