384 HERBERT P. JOHNSON. 



(p. 274) : " Es kann somit kein Zweifel sein, dass bei Ophriotrocha 

 Hermaphroditismus vorkommt und es koenne sogar maennliche 

 und weibliche Geschlechtsprodukte zu gleicher Zeit von ein und 

 derselben Keimdruese gebildet worden, aehnlich wie dies in der 

 Zwitterdruese der Opisthobranchier und Pulmonaten der Fall ist." 



There is a strong approach to regional hermaphroditism in 

 Ophriotrocha. The most anterior somites of the genital series 

 produce only male gonads and the female elements become more 

 and more predominant towards the posterior end. 



Korschelt distinguishes in Ophriotrocha four sexual phases : 



1. Pure females. Male genital products not detected at any 

 stage of development. 



2. Pure males. Ova not found. 



3. Apparent females. Well-developed female gonads and free 

 ova. Also, male genital products both mature and immature. 



4. Apparent males. Well-developed male gonads and multi- 

 tudes of spermatozoa ; ova also present in the gonads. 



When both male and female elements are present in the same 

 somite the male are found to be much further developed than the 

 female. These individuals Korschelt believes are functionally 

 males until the female gonads are ripe, whereupon they assume 

 the role of females. There thus occurs a protandric herma- 

 phroditism by which self-fertilization is prevented. 



Something of the same nature, but with the order of events 

 reversed, was observed by Miss Gregory ('05) in Sabella microph- 

 thalmia. Specimens examined in April and early part of May 

 were pure females ; in August all specimens were either herma- 

 phrodites or females, the latter increasing in proportion as the 

 season advanced. Pure males were not found at any time. 



From the few examples that have been sufficiently studied to 

 show the true nature of hermaphroditism in the Polychaeta, it is 

 clear that it is highly variable in its manifestations, and hardly 

 of fixed character even in the forms where it appears to be most 

 firmly established. This condition taken in connection with its 

 sporadic distribution leads naturally to the conclusion that it is 

 of comparatively recent origin in the group. 



In conclusion, it is a pleasure to make grateful acknowledg- 

 ment of my indebtedness to Dr. J. Percy Moore, of the University 



