抄録
Using a total of 60 inbred C_3HF_3 mice, a series of experiments of tabacco tar paintings on the back skin was conducted for approximately 12 months, which, however, apparently failed in developing tumor in these animals. The results of the experiments were summarized as follows. 1) No change whatever was observed in the local skin of the animal where aceton was smeared as control. 2) Pigmentation and thickening of the local skin were observed in the group of animals where a mixture of aceton and tabacco tar was applied. 3) Pigmentation, thickening and loss of hair in the local skin were also observed in the group of animals where a mixture of aceton, tabacco tar and croton oil was applied. 4) The development of spontaneous tumor was observed in 4 out of 60 animals examined.
