Genetics of Hybrid Sterility

IT is a remarkable fact that the disturbances connected with genic sterility in hybrids between species (or races) are paralleled within species by similar disturbances caused by single genes. For example, there is an analogy between the asynaptic mutations in several plants and genic asynapsis in hybrids and likewise between the polymitotic mutation in Zea and the spermatogenesis in Drosophila pseudo-obscura hybrids. Similarly, I have recently found a property analogous to the long-chromosome mutation in Matthiola in a grasshopper hybrid, the chromosomes of which also show a sort of ‘stickiness’ reminding one of the ‘sticky’ mutation in Zea1. Dobzhansky has several times directed attention to this parallelism2, though he does not seem to think it has any deeper genetical significance. In my opinion, there is, however, a possibility of putting the two phenomena on a common basis.