328 FUNCTIONS AND INSTINCTS. 



canals by a single push with a small syringe, 

 but he could not make it pass upwards beyond 

 two joints which seemed to indicate the exist- 

 ence of valves opening only in one direction. 

 He says there is no anal orifice, but other au- 

 thors expressly mention one, and it is not easy 

 to conceive, if the last has no orifice, how the 

 joints can increase in number and remain con- 

 catenated. The body is composed of a vast 

 number of joints, each having an organ where- 

 by it attaches itself: those nearest the head are 

 always small and they enlarge gradually as they 

 recede from it. The extremity of the body ter- 

 minates in a small semi-circular piece. 



Sir Anthony suspects that the several joints of 

 the tape-worm are separate animals. This is an 

 old opinion and has been adopted by several zoo- 

 logists, but Bonnet seems to have proved, that 

 however extended, the tape-worm is only a single 

 animal. Whilst a living head remains attached 

 to some joints, this creature maintains its station 

 and keeps augmenting their number, but when 

 any are broken off, they appear not to form new 

 heads, as Sir Anthony supposes, but die and are 

 expelled from the body. Their nutriment is 

 probably derived from the gastric, pancreatic, 

 and other juices which perpetually flow into 

 the stomach and intestines of the animals they 

 infest ; and they employ the tentacular rays as 

 a mean of irritation to determine a greater se- 

 cretion of these fluids. 



