Abstract
The amoebocytes, which form the most abundant type of blood-cell in Rhodnius, contain rounded, oval, or rod-shaped inclusions which stain by the periodic acid/Schiff method. These are believed to be neutral mucopolysaccharides. The amoebocytes apply themselves to the basal membranes, which likewise are PAS-positive, and appear to contribute to these membranes by discharging their contents. They insinuate themselves into the developing muscles and give rise to the sheaths of connective tissue by which the muscle fibres are surrounded. And they collect around deposits of injected Indian ink, producing similar sheets of PAS-positive material, presumably mucopolysaccharide. The chitinous endocuticle is PAS-negative (except in a few special regions such as the neck and the conjunctival membranes of the limbs). It becomes positive during digestion by the moulting fluid. The tracheae react similarly. Other PAS-positive structures which are not produced by the amoebocytes are the striated border of the mid-gut, the basement membrane of the gut, the perilemma around the ganglia and nerves, and the ground substance within the ganglia.