WHIP-WORM 661 



soluble in milk, and where these drugs are given it is a good idea 

 to mix them with some form of ground feed or cooked mash, and 

 fed in this manner. The same plan as above outlined should be 

 followed to prevent the larger and more active animals getting an 

 overdose to the detriment of the unthrifty ones. It is these un- 

 thrifty animals that probably have the most worms, and care must 

 be taken to see that they get the proper dose of the drugs. 



WHIP-WORM (TRICHOCEPHALUS CRENATUS) 



This parasite is much less common in the United States than the 

 common round- worm which has just been described. It is a much 

 smaller worm, and, instead of being found in the small bowel, 

 as in the case of the round-worm, this parasite is found in the 

 beginning of the large bowel, where it is to be seen firmly attached 

 to the lining membrane. 



Description. — This parasite is only about 1| to 2 inches long, 

 and at its small end is only a little larger than an ordinary hair. 

 The worm has a very peculiar appearance, due to the fact that the 

 posterior part of the body is much larger than the anterior part, and 

 this gives to the parasite an appearance rather similar to that of 

 the old-fashioned black snake cattle whip. In the male parasite 

 the thin portion of the body is coiled up like a whip, while in the 

 female this part of the worm is straight or but slightly curved. 

 The female parasite is also slightly larger than the male, but this is 

 not marked enough to be plainly noticeable. Both the male and fe- 

 male are of a white or pinkish-white color. This worm differs 

 from the round-worm, in that it attaches itself firmly to the Hning 

 membrane of the bowel and derives its nourishment from sucking 

 of blood. 



Source of Infestation. — The source of infestation with this para- 

 site is quite similar to that seen in the case of the Ascaris suilla. The 

 ova or eggs pass out of the body with the feces, and are scattered 

 about the pastures, entering shallow pools of water and contami- 

 nating articles of food that come in contact with the egg-bearing 

 manure. This egg-contaminated water and food again reach the 

 digestive tract of the hog by being taken in through the mouth. 

 In the stomach of the hog these eggs rapidly hatch, and the mature 

 parasite develops in about four weeks. Through some peculiar 



