The Role of the Epidermal Cells in the ‘Migration’ of Tracheoles in Rhodnius Prolixus (Hemiptera)

Abstract

1. The tracheal system can be injected with a mixture of olive oil and light petroleum, and fixed with osmium tetroxide followed by ethyl gallate. This provides simultaneous demonstration of tracheoles and mitochondria. 2. During moulting in Rhodnius the lining of the tracheoles (which is not shed) is joined to the new cuticle of the trachea by a ring of cement substance which stains deeply with osmium and ethyl gallate. 3. The epidermal cells are responsible for the ‘migration’ of air-filled tracheoles into regions deprived of their normal, tracheal supply. The cells give rise to contractile filaments, sometimes 100µ in length, which become attached to the tracheoles and draw them inwards. 4. Contractile cytoplasmic strands from the epidermal cells probably ensure the even distribution of the tracheoles. They become much more numerous if the insect is exposed to a low concentration of oxygen.