NOTES ON THE EREE-LIVING NEMATODES. 



433 



Notes on the Free-Living Nematodes. 



By 



F. A. Potts, M.A., 



Fellow of Trinity Hall. Cambridge, and Demonstrator of 

 Comparative Anatomy in the University. 



With 11 Text-fisures. 



I. — The Hermaphrodit8 Species. 



CONTKNTS. 



PAGE 



Introduction ...... 433 



Summary of Sexual Phenomena in the Hermaishrodite 



Species ...... 435 



Systematic Part ..... 437 



Biology of the Soil Nematodes in Relation to the Methods 



of Experiment ..... 443 



The Males of Hermaphrodite Species . . . 446 



(1) Structure and Organisation . . . 446 



(2) Proportions of Males in Hermaphrodite Species . 452 



(3) Sexual Instincts of the Males . . .461 

 The Hermaphrodites in Hermaphrodite Species . . 462 



(1) The Hermaphrodite Glands in Rhabditis and 



Diplogaster .... 462 



(2) The Fertility of the Soil-Nematodes . . 468 



(3) Partial Hermaphroditism . . . 473 



(4) The Nature of Hermaphroditism in the Nematoda . 475 



(5) Self -fertilisation in Animals . . . 479 

 Summary of Results ..... 483 



Introduction. 



Orley divided the Nematoda into three groups, roughly 

 corresponding to differences of habitat found in the phylum. 

 (1) Nematozoa embracing all parasitic forms, (2) Rhabditi- 

 formge which live free in '"' decomposing organic substances 



VOL. 55, PART 3. NEW SERIES. 



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