242 IOWA DEPARTMENT OF AGRICULTURE. 



suilla are the most important. In the mature form the echinorrhynchus 

 infests the small intestines, particularly the duodenum. It may be found 

 free or fixed to the mucous membrane. Because of its presence there is 

 considerable irritation and the perforation of the intestinal wall may occur 

 in some cases. There is scarcely ever found more than five or six of 

 these worms in the intestines. Their presence means a serious loss not 

 only to the breeder, but also to the packer because of the damage done 

 to the intestine which is used in the manufacture of sausage casings. 



The male of this species is from two to three and the female from 

 seven to eleven inches long. The ova are laid in the intestine of the pig 

 and afterwards escape with the bowel discharges. They ai'e then swal- 

 lowed by the larval form of the May beetle. It seems probable that the 

 larval stage may be passed through in a number of invertebrates which 

 are in turn devoured by the pig and the larva set free, and then developes 

 into an adult worm. The symptoms are those of other intestinal worms, 

 and little can be done in the way of treatment. By way of prevention 

 in infected localities pigs should be shut up and their discharges burned 

 or saturated with mercuric chloride solution to destroy the embryos as 

 soon as hatched, and in this way the cycle of development is brolven 

 oecause the pig will find no invertebrate which harbor the larvae. 



The common round worm, known scientifically as the ascaris suille, 

 inhabits the small intestines, the male being about six inches and the fe- 

 male about ten inches in length. The body is white, firm and pointed at 

 both ends. They are usually found in pigs out of condition and vary in 

 numbers from 10 to 20 for each individual. When these parasites are 

 present in small numbers they do little harm, but when pigs are kept con- 

 tinuously in the same pen, or when they drink water that has drained 

 from other pens or sheds they often appear in great numbers, produce 

 serious intestinal disorders, vomiting, emaciation, obstruction of the bow- 

 els and a watery diarrhoea. The treatment includes both preventive and 

 curative. Under the rules for prevention we consider the sanitary condi- 

 tion under which the pigs are kept. Water should not be used from a 

 shallow or contaminated well. Clean feeding floors and watering troughs 

 should be provided, and wallow holes should not be allowed to form in 

 the yards. One of the simple forms of treatment consists in giving tur- 

 pentine in milk, about one teaspoonful to a pig weighing one hundred 

 pounds. This should be given on an empty stomach, and two or three 

 doses several hours apart. 



The mode of reproduction is in fact one of the principal factors that 

 determines the condition under which parasitism shall take place. Some- 

 times complete evolution of a species only requires one host, sometimes 

 it demands two, successive and, in general specifically different hosts. 



Much interest is centered on the study of parasites because of the dan- 

 ger of infesting man. From our knowledge of the modes of infestation 

 we know that animals can be rendered absolutely safe from the attacks 

 of parasites, but in order to accomplish this we must enforce cleanliness 

 and various other sanitary measures, and see that they get pure air to 

 breathe, water to drink and food to eat. 



In dealing with the parasites that infest the skin, the animals at- 

 tacked should be isolated and the place where they occupy thoroughly 



