PARTHENOGENESIS AND THE INHERITANCE OF COLOR PATTERNS IN THE GROUSE LOCUST PARATETTIX TEXANUS HANCOCK

¹ Department of Zoölogy, Kansas Agricultural Experiment Station.

1. There is indication of a genetic factor, or a group of complementary factors responsible for parthenogenesis in these grouse locusts.

2. The hypothesis of Peacock and Harrison (1925, 1926) that parthenogenesis is consequent upon hybridity is probably further supported if it be provided, as these authors did not, that it is necessary to bring together in the processes of hybridism the specific complementary, or climaxing genetic factors which may cause the development of unfertilized eggs.

3. The members of the species Paratettix texanus Hancock are bisexual, the fertilized eggs producing males and females in equal numbers, and parthenogenetic, the unfertilized eggs, with rare exceptions, hatching females.

4. A mated female may have part of her ova fertilized, and also produce from unfertilized ova, by parthenogenesis, an additional number of offspring which are nearly always females.

5. The segregation and crossing over of factors occur in individuals reproducing by parthenogenesis to the same extent as in those reproducing bisexually.

6. If fertilized, the egg proceeds with the second polocyte division and develops bisexually. In the absence of the fertilizing sperm the last polyocyte division does not occur, or if it does the polar body is not eliminated. If the specific complementary gene, or genes responsible for initiating parthenogenesis be present, diploidy is retained, or restored, and development may begin, consequentially as a kind of artificial parthenogenesis.

7. The progeny from unfertilized eggs are usually homozygous for all the factors they carry, though rarely one proves to be heterozygous for factors.