Studies on Embryonation and Hatching of the Eggs of the Dog Whipworm,Trichocephalus vulpis ∗

Abstract

Summary and Conclusions

(1) Since Trichocephalus vulpis eggs are stimulated in their development by previous subjection to mechanical agitation by centrifugalization, and to immersion in brine, the results of studies on these, and probably other nematode eggs subjected to these influences are not applicable to eggs developing in nature. (2) Sodium chloride in low dilutions (1/1000 N to 1/10 N solutions) stimulates the embryonation of T. vulpis eggs. Higher concentrations (1 to 3 N solutions) inhibit development, collapse the inner layer of the egg shell, and finally kill the embryo. It is not unlikely that other salts present in the soil in small concentrations may also influence the embryonation of these eggs. Thus, the salt content of soils may conceivably play an important role in the epidemiology of whipworm disease. (3) From 25% to 50% of T. vulpis eggs can be hatched by subjecting them in turn to artificial gastric juice for 20 hours and artificial pancreatic juice for 2 hours. The fact that eggs must remain in the gastric juice for a period of time before they will hatch in pancreatic juice suggests that the rapidity with which eggs pass through the stomach of the host may influence the rate of hatching, and thus the resulting intensity of infection in the host.