RHYTHMICITY OF EGG-PRODUCTION BY HELIGMOSOMOIDES-POLYGYRUS IN WILD WOOD MICE, APODEMUS-SYLVATICUS

The rhythmicity of egg production by Heligmosomoides polygyrus (Nemato da) in wild caught wood mice (Apodemus sylvaticus) was studied. Faecal production followed a 24 h cycle, with peaks at 0400 h and troughs at 1300-1900 h. The patterns in eggs per gram of faeces (EPG) and total eggs were similar to each other, though the former was more accentuate d. Both of these followed a 24 h cycle, with peaks coinciding with tro ughs in faecal production and vice versa. Faecal weight was inversely correlated with EPG, but was not significantly correlated with total e ggs. The pattern in EPG presumably reflected the effect of faecal prod uction on the total eggs excreted in each 3 h period. The observed cyc le in total eggs probably describes the pattern of egg production by t he worm, although other factors, such as the host's intestinal rhythms , may contribute to this cycle.