Studies on the haemocytic reaction ofGammarusspp., and its relationship toPolymorphus minutus(Acanthocephala)

Abstract

The haemocytes ofGammarus, which are part of the environment ofP. minutes, have been found to react by encapsulation, against a variety of foreign bodies, wounded tissues and interspecific transplants. Cuticular wounds appear to present the most urgent stimulus to the haemocytes. The haemocytic reaction is not suppressed by X-irradiation. Differences in haemolymph salt concentration betweenG. pulexandG. duebenido not appear to be responsible for the failure of transplants of tissue fromG. pulextoG. duebeni.It is concluded that the haemocytic reaction ofGammarusis very similar in response and nature to that of insects.HealthyP. minutusdoes not stimulate the haemocytic reactions of its hosts, but wounded or damaged parasites are encapsulated. The capsule of connective tissue, which surrounds the parasite during its development in the haemocoele of the intermediate host, appears to be essential for the parasite's survival.I am most grateful to Dr P. Tate for helpful discussions, and Dr George Salt, F.R.S., for his advice and criticism of the manuscript. I also wish to thank Drs H. Laser and B. E. B. Moseley for irradiating the amphipods for me.