THE SEGMENTAL ORGAN OF PODARKE OBSCURA. 



LOUISE HOYT GREGORY. 



In 1892 Goodrich 1 described "A New organ in the Lycor- 

 idea." A ciliated organ found on the dorsal side of the body, 

 paired in every segment except the first and last few. The ne- 

 phridium was found to be a well-developed organ, opening into 

 the body cavity by a ciliated nephrostome. The narrow and 

 tortuous character of the nephridial tube made it impossible to 

 conceive of its acting as a genital duct considering the large size 

 of the eggs. A comparison of the dorsal ciliated organ with the 

 genital funnels of the capitellids described by Eisig — however, 

 suggested the idea that the dorsal ciliated organ might function 

 as a genital funnel. Goodrich could discover no external pore, 

 nor was he able to observe the discharge of the genital products. 

 Yet he considered it possible that the external pore might be 

 formed only at maturity. 



In the spring of 1905, Professor Wilson suggested that I ex- 

 amine this question by the study of sexually mature individuals of 

 Nereis and at the same time work out the method of the dis- 

 charge of its sex products. Heteronereis material, found in 

 abundance at Woods Hole, was collected in the summers of 

 1905 and 1906 but no definite result was obtained on this 

 form. In the case of Podarke obscura, however, I had better 

 success, and although the results conform in general to the work 

 of Goodrich on other members of the family Hesionidse, yet they 

 may be sufficiently different in detail to warrant their description. 

 The material was collected in July and August, 1905, and in 

 June and July, 1906. Mature females were fixed before the 

 time of discharge (which takes place regularly between 7-9 p. 

 m.), 2 during the period of discharge, and after the eggs had been 

 passed out from the body. Immature specimens, collected in 



1 Goodrich, E. S., " On a New Organ in the Lycoridea and on the Nephridia in 

 Nereis diversicolce,' n Quarterly Journal of Alicroscopical Anatomy, 1 892-3, vol. 34. 



2 Treadwell, A. L., " Cytogeny of Podarke obsctira,^ Journal of Morphology, 

 1900-1, vol. 17. 



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