494 



Fehlen jeder Spur einer Umwandlung der Beine des 7. 

 çf Rurapfdoppelsegmen tes zu Copulationsorganen, hat 

 Schmidt fast ganz außer Acht gelassen.« Wenn er nun darauf mit 

 jenen citierten Worten antwortet, so erregt das unwillkürlich Heiter- 

 keit und erinnert an gewisse Abwege, aufweiche die heutige Zoologie 

 durch übertriebene Histiologie theilweise verleitet ist \ so daß manche 

 Autoren den »Wald (Organe) vor Bäumen (Zellen) nicht mehr sehen«. 

 19. November 1896. 



5. Nephridia and Genital Ducts. 



By Edwin S. Goodrich, University Museum, Oxford. 



eingeg. 22. November 1896. 



In the last No. of the Zoologisches Centralblatt (vol. III. No. 22) 

 Prof. R. S. Bergh has reviewed ray paper "On the Coelom, Genital 

 Ducts and Nephridia" (Quart. Journ. Micr. Sc. v. 37. 1895). It is a 

 great privilege for me to have had my work criticised by so compe- 

 tent a reviewer, and one whose observations form no inconsiderable 

 part of the evidence on wich is built the theory there advocated; yet, 

 I cannot help thinking that Prof B e rgh has\omewhat misunderstood 

 my position. He makes the statement, and lays great stress on it, that 

 the foundation of my argument lies in the assertion that the "true 

 nephridia" are always derived from the ectoderm (»die echten Nephri- 

 dien seien immer ectodermalen Ursprungs«) : now, I was particularly 

 cautious not to make this assertion, and not to rest any conclusion 

 merely on whether the rudiments of the nephridia are derived froin 

 this or that germ-layer, a question of secondary importance. I con- 

 sider, therefore, that Prof. Bergh's lengthy criticisms on this point 

 are entirely beside the mark. Nevertheless, as I pointed out, there is 

 considerable evidence in favour of the view that the "true nephridia" 

 are of epiblastic origin; and should this be proved true, it cannot be 

 denied that it might be considered as important additional evidence 

 for the theory. Personally, I am not enclined to attach overwhelming 

 importance to the often uncertain details of embryonic development, 

 which seem to be less trustworthy than the broad teachings of compa- 

 rative anatomy. It appears, however, that here we have a case in 

 which the conclusions derived from anatomy are fully confirmed by 

 observations made in embryology. The one thing essential for the 

 theory (denn damit steht oder fällt meine ganze Theorie) is that the 



* Diesen Vorwurf will ich übrigens gegen Herrn P. Schmidt im Allge- 

 meinen nicht erheben! 



