The effect of changes in the osmotic pressure upon Hammerschmidtiella diesingi (Hammerschmidt, 1838) with reference to the survival of the nematode during moulting of the cockroach.

It was observed that Leidynema appendiculata (Leidy, 1850) and Hammerschmidtiella diesingi (Hammerschmidt, 1838; Chitwood, 1932), which are nematodes parasitic in the hind-gut of Blatta orientalis L., could survive in the hind-gut when the cockroach moulted and it was decided to see what effect moulting of the cockroach had upon the nematodes. In moulting cockroaches there is a certain amount of drying in the gut which presumably increases the osmotic pressure of the gut contents. The nematodes in moulting cockroaches are found inside the cast peritrophic membrane of the gut, have a shrunken appearance and are rather inactive. By examining the nematodes at various times after the insects had moulted it was found that the cast peritrophic membrane becomes broken up in the middle section of the hindgut. The nematodes, which have at this stage become more active, escape from the broken membrane and move up to their normal position in the hind-gut. The shrunken appearance of the nematodes suggested that they were in a hypertonic environment. It was therefore decided to observe the effect of various concentrations of 1-0 M sodium chloride, 1-0 M sucrose, and sea water upon the adult female nematodes to determine if they were capable of surviving long exposures to these solutions and to see if there was subsequent recovery in isotonic solutions.