ANNULOIDA ! SCOLECIDA. 



145 



2. The proscolex, or the minute embryo which is liberated 

 from the ovum, when this latter has been swallowed by any 

 warm-blooded vertebrate. 



Fig. 39. Morphology of Tfeniada. 1. Ovum containing the embryo in its 

 leathery case. 2. Cystice-rcus longicollis. 3. ' Head ' of adult Taenia f.olium 

 enlarged, showing the booklets and cephalic suckers. 4. A single genera- 

 tive joint, or proglottis, magnified, showing the dendritic ovary (o), the 

 generative pore (a), and the water-vascular canals (6). 5. A portion of 

 a Tape- worm (strobila,), showing the alternate arrangement of the gene- 

 rative pores. 



3. The scolex, or the more advanced, but still sexually im- 

 perfect, embryo, into which the proscolex develops, when it 

 has encysted itself within the tissues of its host. (Under this 

 head come the so-called * Cystic Worms.') 



4. The strobila, or adult Tape-worm, into which the scolex 

 develops itself, when received into the alimentary canal of a 

 warm-blooded vertebrate. The strobila is constituted by the 

 ' head,' and by a number of immature and mature generative 

 segments or joints, termed the 'proglottides.' 



The subject will, perhaps, be more clearly understood by 

 following the development of one of the common Tape- worms 

 of man, viz. the Tcania solium. Commencing with an indivi- 

 dual who is already suffering from the presence of this para- 

 site, one of the most distressing symptoms of the case is found 

 to be the escape of the joints of the animal from the bowel. 

 These joints are the ripe ' proglottides,' containing the fecun- 

 dated ova. When the ova which are microscopic in size 

 are liberated by the decomposition of the proglottis, they may 

 gain access to water, or be blown about by the wind. In 



VOL. I. L 



