ABSTRACT
A characteristic feature of scientific progress during the last half-century has been the rapid development of biology as an experimental science. It may be that we are now standing on the threshold of an era of biological inventions, inventions whose impact on social habit will be more far-reaching than that of mechanical invention in the nineteenth century. If we could foresee the outcome, they might seem to most of us quite as fantastic as the discovery of television would have seemed to our grandfathers. The substitution of the incubator for normal maternity is already less improbable than it must have seemed to most readers of Daedalus when Professor Haldane first published his diverting speculations. Within the last two years the rabbit embryo has been cultured in glassware up to and beyond implantation. A Russian scientist now claims that he can separate the seminal fluid of the rabbit into portions, one containing the male-producing element and the other the female-producing element. There is no theoretical reason why a similar method should not be applied to man. Sex-determination by artificial introduction of separated seminal fluid may be practised before many more years have passed. Virgin birth brought 99about by physicochemical agencies, first carried out with sea-urchin eggs in the ‘nineties, has been well-nigh achieved with the rabbit. Fatherless embryos have been produced, and though no mammal has yet been reared to maturity from an unfertilized egg in the laboratory it is quite possible that this will be done. If it ever is accomplished, human beings may be able to produce families by a method which has always proved singularly attractive to mystics. Probably mammals produced without fertilization would prove to be females. If this were so, the male sex would become unnecessary for the continuance of the race. Further research into the environmental and hereditary factors which affect multiple births may suggest another kind of biological invention. If twin births were the rule rather than the exception a new class of population problems would arise.
