The trend in agricultural parasitology in the past two decades has been to emphasise the importance of studies on the cycles of nematode parasitism in farm animals. However, singularly little work has been directed towards and elucidation of those factors in the environment of the host and free living larval parasites which are important in the acquisition of parasitic infestations.
The object of this investigation is to study the growth of a common nematode parasite of sheep in an attempt to determine the 'age' of a population. The term 'age', as used here, denotes the time from infestation to the death of the worm. [From introduction.]