468 THE DISEASES AND DISORDERS OF THE OX. 



stitutes the first segment, and after it come the generative 

 segments, which are called " proglottides," which are produced 

 by a process of budding from the head. The youngest segments 

 are narrow and soft, and compose the " neck/' or part nearest 

 to the '* head," and those which are farthest away from it 

 are the most mature. In fact, as we pass from the head, 

 the segments gradually become broader and longer, and more 

 distinct from one another. The hindmost segments are the 

 largest, possess the power of separating themselves, and that of 

 leading for a short time an independent life. They escape from 

 the body, the ripe eggs with their hard shells retaining their 

 vitality, and their readiness to undergo a series of changes which 

 culminate in the adult tapeworm. If all the rest of the worm 

 be removed, the head alone being left, the whole creature will 

 again be gradually reproduced. 



Hence it is very difficult to remove a tapeworm when it has 

 once taken up its position in the interior of a man or animal. 

 Those who have the grievous misfortune to be afflicted with a 

 tapeworm well know the immense inconvenience occasioned by 

 the entozoon, and the tenacity of its existence, and the physician 

 knows only too well how difficult it is to cause the expulsion of 

 the little head. This is, in the case of some tapeworms, of about 

 the size of a pin's head, and when it is magnified, its sides are 

 seen to be provided with four *' suckers," by means of which it 

 fastens itself to the wall of some part of the alimentary canal. 

 In addition to these sucking discs, some tapeworms are possessed 

 of circles of hooks placed in front of the suckers. These 

 hooks have sharp projecting points, which serve as anchors for 

 the tapeworm. 



The tapeworms of the ox may be as much as 50 ft. or even 

 100 ft. long ; but that of the cat is very much shorter. The 

 head of some tapeworms is provided with hooks, while that of 

 others is devoid of hooks, e.g. the head of the tapeworm of the 

 sheep, and also that of the ox, have no hooks. There are six 

 different kinds of tapeworms met with in animals. To one of these 

 divisions the name Tetrarhynchidse is given. Examples are found 

 in the sun-fish. They are provided with numerous spines on the 

 head, and by means of these they tunnel about in the body 

 of their host. Sometimes the liver of the sun-fish is simply 

 nothing more than a bag full of these worms. 



