Slide showing ten photographs of 'the effects on development of a mutation in the house mouse.' Slide showing ten black and white photographs of 'the effects on development of a mutation in the house mouse.' There are photographs of homozygotes, normal mice, embyros and heterozygotes. Title below images reads: 'Fig. 141. - The effects on development of a mutation in the house mouse. Above, from left, normal embryos of 9, 9 1/2, 10 1/2, 11, and 16 1/2 days of development; below, littermates of above, showing homozygotes at 9, 9 1/2 and 10 1/2 days and heterozygotes at 11 and 16 1/2 days. The homozygotes at 10 1/2 is shown just before death and lacks tail bud and hind limb buds. In the heterozygote at 11 days the constriction in the tail marks the end of the notochord; By 16 1/2 days the end of the tail has been resorbed. (After Chesley.)' Late 19th to early 20th century