THE GENE 28-5 



by transforming mechanisms of the type described above. Since 

 transforming mechanisms insuring an excess of wild-type progeny 

 should have considerable survival value, they may be widely distrib- 

 uted in Nature. If this be true, Mendel's law is a special case of a 

 general theory governing the transmission of inherited characters. 

 Many injuries could be immediately "repaired" following copulation 

 with a sufficiently vigorous gamete, especially one which carried a 

 large volume of physiologically normal cytoplasm. The current 

 view that the large volume of cytoplasm in the egg is for nutrition 

 as consumable nutrients may require qualification; the egg cyto- 

 plasm may also serve to carry a high concentration of a variety of 

 gene -products which would insure maximal gene-product to gene 

 equilibria. Some of the gene -products may be derived from the 

 normal alleles which were discarded in the polar bodies, but whose 

 gene -products are still represented in the cytoplasm. 



NUTRITION AND THE INTEGRITY OF THE GENOME 



The theory throws a new light on the perennial dispute of the 

 respective effects of nutrition and heredity on the characteristics of 

 an individual. Genes controlling hydrolysis or fermentation of sugars 

 may be degraded by poor nutrition to the point where they are unable 

 to produce their respective enzymes. This effect can be produced 

 merely by dissimilating the cells in a substrate deficient in essential 

 nutrients such as phosphate buffer, or culturing them on a synthetic 

 medium capable of promoting poor, rather than vigorous, growth. 

 The degraded cells temporarily lose their fermentative or hydroly- 

 tic ability in regard to galactose, melibiose or maltose but regain 

 it after growth in a nutrient capable of promoting vigorous growth 

 even though the specific substrate on which the enzymes act may be 

 absent from the medium. The enzymes acting on these sugars are 

 under gene control indicating that the degrading effect of the poor 

 nutrition acts directly on the gene. This view is confirmed by geneti- 

 cal tetrad analyses which prove that direct interchange of gene ma- 

 terial occurred between loci in the heterozygous condition. These 

 conclusions help to reconcile the differences of opinion between prac- 

 tical plant and animal breeders and theoretical geneticists. Mendelian 

 ratios are achieved by theoretical geneticists because they have se- 

 lected organisms with completely degraded genes which are relative- 

 ly unaffected by environment and have assumed that environment has 

 a limited ability to alter the gene. Practical breeders, on the con- 

 trary, use organisms in which naany genes are sensitive to both en- 

 vironment and nutrition, and many of them believe that an organism 

 is fully competent of transmitting its entire complement of heredi- 

 tary material only if it is nurtured with the best possible nutrients. 

 By the same token, an organism which is genetically weak, but not 



