The reactions of Schistosoma mansoni miracidia to light

The reactions of Schistosoma mansoni miracidia to artificial light were studied by direct observations, choice-chambers and a photographic technique, at room temperature and at 15 C. The miracidia responded positively to directed illumination, but did not aggregate in a lighted dish. Photography indicated an orthokinetic response to light intensity, but sharp changes in light intensity had no detectable effect on miracidial behavior. At the lower temperature the response to a directed light beam was almost completely inhibited and the orthokinetic response could no longer be demonstrated.