176 DISEASES . OF SWINE 



digestive tract along with the food, usually the 

 drinking-water. Four weeks after reaching the 

 intestines, eggs that contain well-developed embryos 

 are said to develop into mature worms. 



Symptoms. — The whip worm seems to cause but 

 little disturbance, even when present in large num- 

 bers. It no doubt irritates the lining membrane of 

 the' caecum, but irritation such as produced, by this 

 parasite does not interfere with the digestion of food 

 to a noticeable degree. When present along with 

 other forms, it no doubt helps in producing symptoms 

 of parasitism. 



THE TREATMENT OF INTESTINAL WORMS 



Preventive Treatment. — The animal parasites that 

 are the most commbn are those having a simple life 

 history. When an intermediate host is required, as is 

 the case with the thorn-headed worm, tapeworms, 

 and flukes, there is a better opportunity to destroy 

 them, and a very small per cent, of the eggs and 

 larvae develop into mature worms. In all forms, 

 however favorable the surroundings 'and simple the 

 life: history, a large per cent, of the eggs perish. 

 But when the conditions are favorable, the eggs 

 and larvae are able to survive for a 'longer time and 

 have a better chance to infect animals and reach 

 maturity. 



Stagnant ponds formed by surface water and in 

 which hogs wallow are favorable places for the 

 lower forms of animal life to incubate and develop. 

 For this reason old pens and pastures, if wet, should 



