[33] OLIGOCH^TOLOGICAL KESE ARCHES. 911 



Other investigators, on the contrary, such as E. R. Lankaster,* op- 

 pose the above advanced theories, and state as their opinions that ovi- 

 ducts independent of the penis will eventually be found, being of such 

 a delicate structure that they have as yet escaped detection. In this 

 case all the organs considered as oviducts should only be parts of the 

 efferent duct and penis. 



That the investigation of this subject is a difficult one is recognized 

 by both Claparede and Lankaster, and both believe that we will always 

 remain in doubt as to the nature of the oviduct, because direct observa- 

 tions of the passage of the ova through the oviduct must be and are 

 extremely difftcult to make. As yet I have not heard of any such ob- 

 servation. 



Before I begin to review thedifferent opinions of Claparede, Vejdovsky, 

 and others upon this subject it will be necessary to first shortly describe 

 the different membranes sheaths, and muscles which I have found to 

 belong to the copulative organs, and some of which I believe must 

 belong to the oviduct. 



The male organ consists in well-developed specimens of two different 

 pans, viz : 



a. Efferent funnel, efferent duct, atrium with prostata and penis. 



h. Penis sheath. 



The different parts under a are all connected with each other, and 

 constitute what is generally known as the " efferent duct." Not so with 

 the penis sheath, which can be considered, in a fully developed speci- 

 men, as an accessory organ; surrounding the penis proper at its lower 

 end, and being open at both extremities, is connected with the penis 

 only, if at all, by minute muscles. 



The efferent duct, with its funnel-shaped aperture, is, next to the 

 atrium, the least variable part of the copulative organ, and constitutes 

 always the upper part of the organ, and is in our j)resent family of 

 Tuhijieidce always single. The middle part, or atrium, of the copulative 

 organ is always thicker and somewhat bent, and furnished with either 

 one single prostata gland, as in Tubificini, or with several ones, as in 

 Telmatodrilini. The cells of the atrium are generally large and distinct, 

 and quite different from those of the efferent duct proper. The interior 

 of the efferent duct is coated with a ciliated epithelium, but in the 

 atrium, or penis proper, this is absent. 



The lower end of the atrium is tapering towards the exterior ai)ex, 

 forming the penis proper. The penis is somewhat differentiated, the 

 cells sometimes having a more regular form and arrangement than those 

 of the atrium. Where, however, the atrium ends and the penis proper 

 begins is impossible to decide upon, as the change from one organ to 

 the other is very gradual, and sometimes even none at all. When the 

 atrium has entered the penis sheath and the oviduct it may, however, 

 be considered as a true penis. 



* Anu, and Mag. of Nat. Hist., Vol. VII, p. 90^100. 



