THE SEGREGATION AND RECOMBINATION OF HO- 

 MOLOGOUS CHROMOSOMES AS FOUND IN TWO 

 GENERA OF ACRIDIDAE (ORTHOPTERA) 



E. ELEANOR CAROTHERS 



From the Zoological Laboratory of the University of Pennsylvania 1 



FIVE TEXT FIGURES AND FOURTEEN PLATES 



CONTENTS 



I. Introduction , 446 



1. Statement of the problem 446 



2. Nomenclature 449 



3. Special fitness of material 449 



4. Methods and acknowledgments 451 



1 1 . Observations 452 



1. First spermatocytes 452 



a. Segregation of homologues of J-shaped tetrads in individual 



number 1. Trimerotropis (?) suffusa (?) 452 



b. Recombinations of homologues of J-shaped tetrads in 



eighty-two individuals of Trimerotropis (?) fallax (?) 456 



c. Segregation and recombination of homologues of J-shaped 



tetrads in eleven individuals of Circotettix lobatus 464 



d. Origin of a tetrad with unequal dyads 465 



e. Other forms of heteromoi-phism 466 



f. Reduced number of chromosomes in Circotettix 46/7 



g. Supernumeraries 469 



2. Spermatogonial metaphases and female somatic metaphases 470 



a. Individual number 1 470 



b. Extremes found in the group 470 



c. Female somatic complexes 471 



3. Second spermatocytes 472 



a. Types found in individual number 1 472 



b. Extremes found in the group 473 



c. Circotettix 474 



111. Summary of observations 474 



IV. Discussion 476 



1. Constancy in individuals 476 



1 Contribution from the Zoological Laboratory of the University of Pennsyl- 

 vania. 



445 



JOURNAL OP MORPHOLOGY, VOL. 2S, NO. 2 



