VERMES. 17 



near its anal end. The ovarian tubes commence as thin fili- 

 form caeca arranged in complicated coils round the intestine. 

 Near the anus however these tubes become suddenly expanded, 

 and extend as far forwards as the anterior third of the body : 

 where they unite to form a short and very narrow oviduct, 

 which opens outwards. This, turning round the intestine and 

 becoming narrow, terminates at the genital aperture one-third 

 from the anterior end of the animal. 



Class III. PLATYELMINTHES. 



28. A Tape- Worm (Tcenia solium). 



The specimen, a mature worm (Strolilia), is a flattened, 

 ribbon-shaped organism, divided by transverse constrictions into 

 numerous well-defined segments the * proglottides,' which are 

 for the most part of large size, but on approaching the head 

 they become gradually smaller, and the constrictions less evi- 

 dent, till in the vicinity of the head the body becomes reduced 

 to a mere flattened thread, and the constrictions are only repre- 

 sented by faintly marked ' striae.' A short, smooth, faintly- 

 striated neck is succeeded by the head. This is about the size 

 of a pin's head, and is armed with a double circlet of minute 

 spines, and carries in addition four minute suckers. The ' pro- 

 glottides ' in the hinder part of the specimen are of a whitish 

 colour, opaque, and three or four times as long as they are broad. 

 The head, 'nurse,' or 'scolex/ is asexual. The segments succeed- 

 ing are sexual, but immature : that is, their generative organs 

 and their products are but imperfectly developed. The segments 

 which succeed and make up the bulk of the organism, are 

 sexually mature, hermaphrodite ' proglottides.' The new seg- 

 ments are produced by a process of gemmation from the head : 

 and the segments thus produced are intercalated between the 

 head and the segments already formed. The apertures of the 

 efferent ducts of the male and female organs are situated on 

 small cup-shaped eminences placed on the lateral margins of 

 the 'proglottides,' the side alternating in adjoining segments. 

 The specimen is eight feet in length, and was taken from a 

 human intestine. 



CL. 2 



