When female mice are treated with light doses of alcohol fumes, (45 minutes a day starting at four weeks) and compared with their untreated sisters from the same litter of inbred lines: a) the time between mating and birth of a litter tends to be lengthened; b) the age at the opening of the vaginal orifice and at the first oestrous shown by smears, is questionably increased; c) the length of the oestrous cycle, the number of corpora lutea, size of litter (father untreated), natal and prenatal mortality, show no modification. 2. In isolated cases when the oestrous cycles were recorded before treatment began, the alcohol was associated with cycles whose length' was roughly doubled; this effect was more frequent when the heavy treatment was used. When female mice are treated with completely anesthetizing doses of alcohol fumes (five days a week starting at four weeks), are mated with normal males, and are compared with their untreated sisters from the same litter and mated with the same normal male: a) the treatment tends to delay the birth of the first litter and increases the intervals of time between successive births, when all young are killed at birth and the mothers remated at once; b) the number of corpora lutea per pregnancy is slightly increased without regard to whether the treatments are suspended during the last week of each pregnancy (series A) or not (series B); c) litter size is reduced by 0,5 mice in series A and 0,7 mice in series B; d) pregnancies yielding no full term young ("zero" litters) are slightly more frequent; e) the proportion of young found dead at birth is increased, in series A by 4,5%, in series B by 9,4%; and in both test and control litters, the proportion of females dead is slightly higher than the males; f) the prenatal mortality is increased by from one to two embryos per litter; g) the sex ratios show no modification: the combined totals give 51,2% males in 2857 mice; h) the occurrence of abnormalities among the young is not influenced.
