ABSTRACT
The only observed effect of rearing haploid and diploid embryos of Xenopus laevis at 16°C instead of 22°C was retarded development. The same proportion of haploids (90–95 per cent) develop the syndrome (oedema, feeble heart, poorly coiled gut) and the stage expectancy is similar.
Haploid tissues may live longer and develop more normally when telo-biosed to diploid tissues, but anterior diploid tissue promotes better development than the same quantity of posterior tissue.
It is suggested that the haploid syndrome develops because haploids lack hybrid vigour completely, and cannot regulate the abnormalities caused by smaller cell size and/or unmasked recessive lethal genes.
An hypothesis is put forward to explain the fact that haploid nuclei are more nearly spherical than diploid nuclei.
