The intradermal studies with the fraction of Ascaris lumbricoides and Toxocara canis were performed to human and dog, and the following results were observed. Wheal and erythema were appeared in the cases of ascaris infection or who had past history, but not in the ascaris free before. The size of wheal reached to peak 30 minutes after the injection. The crude antigen had specificity and showed no cross reaction. The crude antigen cause the strongest and largest reaction than the other substances; protein, polysaccharide and the mixed antigen. No cutaneous reaction was observed with the fraction of polysaccharides. The size of wheal did not parallel with the worm burden. The skin reaction was appeared four weeks after the infection.
