Dr. Holló Ferenc szerk.: Parasitologia Hungarica 3. (Budapest, 1970)

medium size adult worms were selected, washed repeatedly in physiological saline, and placed in glass vessels. Male and female worms were allocated in equal number in each series of experiments. Physiological saline was used for control preparations and for dissolving tetramisole;according to some workers, and to our preliminary studies, worms can be kept alive in physiological saline for 8-10 days. Erlenmay

er-flasks of 300 ml capacity

,containing 200 ml of testsolution, were used in the experiments. Dilutions of tetramiso le were prepared as follows: Worms in test solutions were incubated at 37 C. In the first series the effect of each dilution was examined on 20 worms in each bath, and the procedure was repeated in two other trials. Vigour was estimated on the spontaneous motion of the worms and on that caused by mechanical as well as light irritation (18). The readings were taken at 1, 2, 3, 4, 5, 6, 12, 24, 48, 72 and 96 hours. After evaluation of the first experiment the effect was observed also at 20, 40, 60, 80, 120 and 180 minutes to make the experiment more complete; ten parallel test-worms were used for each concentration, and the procedure was repeated once. A study on the reactivation of worms exposed to the drug was carried out in the second series of experiments. Worms, having been exposed to the drug for 3 hours, were rinsed with and put into physiological saline and incubated at 37° C; their behaviour was observed at 20, 40, 60, 80, 120, 180 mi1,00 mg/200 ml 0,50 mg/200 ml 0,10 mg/200 ml 0,05 mg/200 ml 0,01 mg/200 ml 5,00 /tg/ml, 2,50 /cg/ml, 0,50 //g/ml, 0,25 /teg/ml, 0,05 /fcg/ml.