Dr. Holló Ferenc szerk.: Parasitologia Hungarica 3. (Budapest, 1970)
nut es and at 24, 48, 72 hours; to check vitality at 72 hours thermo-irritation was also carried out. Results The result of the first series of experiments is shown in Talles 1 and 2 . The worms were paralysed by low concentration of tetramisole shortly after coming in contact with it. At a concentration of 1 mg tetramisole/ 200 ml more than 50 $ of the worms stopped moving within 20 minutes, while all worms had done so after 80 minutes. In the solution containing 0,5 mg drug/200 ml paralysis of all worms was complete by 3 hours. Although a paralysing effect at lower concentrations (0,10 and 0,05 mg/200 ml) was observed from the outset of the exposure, it was complete on all worms only by 48 and 72 hours,respectively. The effect of 0,01 mg drug/200 ml was first detected after an exposure of 48 hours and it caused paralysis in about one half of the worms by 96 hours.No sex differences in sensitivity to the drug were found. According to readings at 24, 48, 72 and 96 hours the worms failed to reactivate in tetramisole . Observations carried out at higher concentrations at 20 minute intervals revealed that cessation of worm movement was not preceded by an excitation phase. The results of the second series of experiments are summarized in Table 3- It can be seen that the paralysing effect of tetra misole is a reversible one; the worms recover in normal saline. The time required for reactivation is dependent on the drug concentration to which the worms had been previously exposed; the higher the concentration that had been used the longer was the period needed for recovery.
