Variation in size of Ostertagia circumcincta,a nematode parasite of sheep,induced experimentally and during preparation and preservation

Summary This investigation was undertaken to determine the effect of formol-saline fixation and subsequent preparation on the length of Ostertagia circumcincta, a gastrointestinal parasite of sheep. Such induced changes in worm lengths were compared with the size distribution in two experimental populations in lambs, one of which was helminthologically susceptible and the other highly resistant. It was concluded that variation in worm length caused by fixation was not significant when compared to the variation encountered naturally in worm populations. ac]19851213