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LIFE, IN ITS LOWER FORMS. 



ened point, the very extremity of which is perforated, 

 forming a mouth through which the juices of the animal- 

 tissue are absorbed into the sac. Here, then, are indubi- 

 table characteristics of a living independent being. Here 

 is a stomachal cavity in which foreign matter is assimi- 

 lated, and this is imbibed through a distinct mouth. 



But more ; a provision is needed for the attachment of 

 the parasite while it is thus drawing its nutriment, and this 

 is given in a twofold mode. First, around the sides of 

 the extremity of the lengthened neck are placed four oval 

 suckers, adapted for adhering to a smooth surface ; and, 

 secondly, around the oval aperture there is a double circle 

 of minute recurved hooks, which, fixing into the surround- 

 ing flesh, anchor the mouth securely, while, at the same 

 time, by the irritation which they produce, they cause the 

 vital juices to flow more abundantly to the wounded part, 

 and thus increase the sustenance of the parasite. 



Other forms differ from this chiefly in the increased 

 number of their organs ; the bladder, for instance, is fur- 

 nished with many such heads, as in that species which in- 

 fests the brain of sheep ; or the head, if single, is a pro- 

 trusile proboscis, armed with many rows of recurved 

 spines ; or, if there be but one head, and that armed with 

 but two rows of hooks and one series of suckers, the neck 

 is greatly developed and divided into a great number of 

 segments, while the bladder is diminished to a compara- 

 tively small swelling at the hinder extremity. 



We are thus brought to consider that horrible pest, the 

 Tape- worm (Tama), which consists of a ribbon-like body, 

 formed of square flattened segments, sometimes amounting 

 to five hundred in number, and attaining an aggregate 



