Haemocoel

The remarkable displacement of the cœlom by an irregularly distended system of blood-spaces, “a hæmocœl” (which, Prof. Lankester has elsewhere shown, takes place in the Arthropoda and Mollusca), is lucidly described in this Introduction.

There seems little doubt that these organs, connected as they are with the haemocoel, and everted by haemocoelic fluid pressure, serve as additional respiratory organs, when the larva is in water too deep to enable it to use its tracheal funnel.

The brood of this wasp are composed of two types of larvae: typical parasitic larvae, which develop into adult wasps, and precocious larvae, which move about in the host haemocoel but die before pupation.