A Cytological Study of the Semi-parasitic 

 Copepod, Hersilia apodiformis (Phil.), with 

 Some General Considerations of Copepod 



Chromosomes. 



Siduey I. Koruhauser. 



Fiom the Zoölogical Institute, "VViii-zbiirg. 



With 9 Textfigiires and Plates XXVII -XXIX. 



Synopsis. 



Page 



I. Introduction 400 



IL Review of Previous Literatiuc 400 



III. Material and Methods 402 



A. Material 402 



B. Methods 402 



IV. Structure of Testes and Ovaries 403 



A. Testes 403 



B. Ovaries 405 



V. Spermatogonia and Oögonia 406 



A. Spermatogonia 406 



B. Üögonia 408 



VI. The Growth Period 409 



A. Spermatocytes 409 



B. üöcytes 416 



VII. The Spermatocyte Divisions 418 



VIII. The Chromosomes of the Cleavage Cells and PrimoBtlial Germ Cells . . 421 



A. Cleavage CeUs 421 



B. Primordial Germ Cells 422 



IX. Discussion 422 



A. Form and Number of the Umreduced Chromosomes 422 



B. Syndesis and the Maturation Divisions 424 



C. Chi-oniosomes and Phylogenetic Relarionslüp 426 



D. The Classification of the Copepods 429 



E. The Hetero-chromosomes and a Case of Hermaphroditism .... 435 

 X. Summary 438 



Bibhography 440 



Explanation of Plates 444 



Archiv f. Zellforschung. XIII. 26 



