DEFINITION OF TAENIA SOLIUM. 



489 



coloured by a hlach pig^nent, and bears a medium-sized rostellum, with 

 generally twenty -six m' twenty-eight hooks, which are distinguished from 

 those of the allied species by their compressed and rather stout form, 

 and by the relative shortness of their roots. Following the head there 

 is a thread-like neck, a centimetre in length, whose segmentation cannot 

 be easily detected by the naked eye. The first segments are extremely 

 short, but those succeeding gradually increase in length, so gradually, 

 however, that they only assume the rectangular form at a distance of 1 

 metre, or even more behind the head. More posteriorly, the ripe segments 

 begin, the sexual organs having been fully developed about 200 joints 

 anteriorly, or at about the 4:50th joint. The ripe proglottides are only 

 rarely spontaneously voided, and generally find an exit, singly or in 

 numbers, along with the excreta. The sexual opening is situated behind 

 the middle of the joint. The uterus, which is generally seen distinctly 

 through the envelopes of the body, has seven to ten lateral branches, which 

 are separated from each other by considerable distances, and in their 

 turn again divide into a number of dendritic or comb-like branches. 

 The eggs are almost round and are enclosed in a firm shell, whose outside 

 is covered with thickly set little rods. Sometimes the origiiial clear egg- 

 msmiirane persists within the shell. 



Fig. 274.— Head 

 of Tcsnia solium. 

 (x i5.) 



Fig. 275.— Half- 

 ripe and ripe joint 

 of T. solium (nat. 

 size). 



Fig. 276.— Two 

 proglottides of T. 

 solium with uterus. 

 (X 2.) 



The corresponding bladder-worm (Cysticercus cellulosee) has a special 

 preference for the muscles of the pig, but is occasionally found in other 

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