STUDIES ON STRONGYLOIDES OF PRIMATES: II. FACTORS DETERMINING THE "DIRECT" AND THE "INDIRECT" MODE OF LIFE

Abstract

Under optimum conditions Strongyloides fülleborni has an indirect life cycle but under adverse conditions, only infective larvae and males are developed. Adverse factors such as pH and consistency of media, absence of food, and unsuitable temperatures appear to act directly on the first-stage rhabditiform larvae developed from the eggs of parasitic females. The potential female larva alone becomes an infective larva, the potential male being unaffected. There is a single free-living generation and all eggs laid by free-living females develop directly into infective larvae. The infective larvae developed directly or indirectly can develop only into parthenogenetic females.