472 E. ELEANOR CAROTHERS 



At all events, in Circotettix verruculatus, we can say in regard 

 to the chromosomes which enter the gametes, just as certainly 

 as of a pair of contrasting unit characters which segregate in the 

 F2 generation, that this one was contributed by the father, that 

 one by the mother. 



In genetical work, unless there is sex-linkage or, as in the case 

 of Nabour's Paratettix, ('14, '17) incomplete dominance, the F2 

 generation must be obtained before an analysis of the gametes 

 of the grandparents can be made. In this work a cytological 

 analysis is made of the chromosomal complexes of both parents, 

 so that we have definite knowledge of what goes into the Fi 

 generation. Since there is no reorganization, an analysis of 

 the chromosomal complexes of the Fi generation gives us at 

 once what in genetical studies becomes evident only on a study 

 of the progeny produced by the union of these gametes. In 

 other words, the chromosomal characters dealt with are natu- 

 rally studied in the germ cells, and it is obvious that the gametes 

 of the Fi generation would, on fertilization, become the F2 

 zygotes. So that, while one would have to wait for the F2 

 individuals to analyze somatic characters, the corresponding 

 analysis of the chromosomes is made on the maturing gametes. 



Thus, with an actual identification of the homologues of given 

 pairs of chromosomes from parents to offspring and with a deter- 

 mination of their ratios of recombination, the parallelism between 

 the behavior of the chromosomes and Mendelian phenomena is 

 complete.^ So able a student of heredity and environment as 



^ Judging from a recent paper by Dr. Harmon ('20), based on Dr. Nabour's 

 pedigreed Paratettix, this form may be favorable for a similar line of investiga- 

 tion. She reports that the type BB has the ends of the third pair of chromosomes 

 hook-shaped and the type CC has this pair rod-shaped, while BC, the hybrid, 

 has one chromosome of each sort. 



There are two obvious weaknesses in her report. There is no statement as 

 to whether father and sons were examined or whether examples of the general 

 population were taken. Nor are there any data as to the number of individuals 

 of the various types studied. 



In any event, it is not shown that there is a correlation between the color 

 pattern and the morphology of this chromosome pair; such a relationship would 

 be suggested if in the F2 BB and hook-shaped number 3's and CC and rod-shaped 

 number 3's segregated together. 



