A CHEMOKINETIC RESPONSE IN SCHISTOSOMA-MANSONI-CERCARIAE

Schistosoma mansoni cercariae have been shown to aggregate in the pres ence of glass slides treated with clear nail varnish and linoleic acid . In choice chambers cercariae move toward the stimulant, but this beh avior is not seen when linoleic acid is omitted. After 30-45 min, the cercariae were concentrated near the end of the choice-chamber contain ing the linoleic acid slide. When the cercariae were added in the cent er of the choice chamber, they formed a diffuse cloud that dispersed s lowly in both directions in the absence of linoleic acid. Cercariae ag gregating in the vicinity of a stimulant surface are not immediately s timulated to commence penetration; this appears to be time and dose re lated.