SPERMATOGENESIS IN PARATETTIX. 1 



MARY T. HARMAN. 



Wilson has said that "heredrity is a consequence of the genetic 

 continuity of cells by division, and the germ cells form the 

 vehicle of transmission from one generation to another." 



If this be true we should look to the structure of the germ-cells 

 fo an explanation of the phenomena that have been and are 

 being found out in heredity. Cytologists have discovered much 

 concerning the structure of the germ-cells and the behavior of 

 the chromosomes during the processes of maturation and division. 

 The combined knowledge of sex and sex ratio, and the cytologi- 

 cal constitution of germ-cells has shown in many forms, at least, 

 a correlation between the inheritance of sex and the dimorphism 

 of spermatozoa or eggs, or both. However, the vast amount 

 of cytological work has been done with forms the behavior of 

 whose characteristics in heredity is unknown. On the other 

 hand, much of the work in heredity has been done with forms 

 of which little or nothing is known of the structure of the germ- 

 cells. It is the writer's good fortune to have access to material 

 of which some of the ancestry is known for eighteen generations, 

 covering a period of five years. 



For a number of years Dr. R. K. Nabours 2 has been conducting 

 experiments with regard to inheritance in Paratettix, a genus of 

 the short-horned grasshoppers. The characteristics used in 

 his investigations are the color patterns of the pronotum and 

 femora of the jumping legs, and the lengths of the pronotum and 

 wings. The data show that the inheritance of the color patterns 

 is Mendelian in its behavior. In the FI hybrid no part of the 

 color pattern of one parent species is ever replaced by the color 

 pattern of the other parent, but the color patterns of both parents 

 are present. Reciprocal crosses give identical results. The 



1 Contribution from the Zoological Laboratory, Kansas State Agricultural 

 College, No. 7. 



2 The writer wishes to thank Dr. R. K. Nabours for the grasshoppers which 

 have furnished the material for this paper. 



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