THE LUNG WORM. 



253- 



THKEAD "WORM, 

 a, mouth. 



The eggs 



half of an inch in length, and the latter has a long hair-like tail with a three-pointed end, the tail of 

 the male being blunt. The body is fusiform, and the front end is narrowed at the truncated head, 

 which is sometimes rendered very conspicuous by a bulging of the transparent membrane which 

 surrounds the mouth. This has three papillae around it, and leads to a triangular oesophagus. There 

 is no doubt that the worm is introduced in the form of an egg. The worms live in the csecum, which is 

 their proper position. They stray to the lower bowel and produce irritation there. 



Several species of Ascaris are parasitic within children and adults, and affect monkeys, horses, 

 dogs, pigs, bears, oxen, mice, birds, and marsupials. The species infecting man and the pig are 

 sometimes identical, and this is the case in the example which must be taken as the type. The large 

 round worm, which measures from four to six inches in length in the male, and from ten to fourteen, 

 in the female, is at first sight not unlike a pale Earth Worm. They are 

 narrowed at each end, and the body is elastic and marked by numerous 

 fine cross striations. This Ascaris lumbricoides is usually found 

 solitary or in small numbers in the upper and middle part of the 

 small intestine ; from 100 to a 1,000 have been found. They wander 

 into the stomach and are cast forth, or they may get up into the 

 nostrils and escape. They may make their way through the coils of 

 the intestine into the cavity of the body, producing inflammation and 

 abscess. 



The Lung Worm* is often fatal to calves, and a closely allied species attacks lambs, 

 and embryos of the Lung Worm are found within the common Earth Worm, which swallows them 

 mechanically, with its food of soil. Cobbold placed some of these embryos, or larvaB, as he calls them, 

 which he got from an Earth Worm, on to the fronds of watered ferns, and he noticed them increase in 

 size and organisation. Doubtless the parasites escape in due time from worms, and are devoured by 

 their next hosts with their vegetable food. They do not go into the stomach, but pass into the 

 bronchial tubes and set up much and often fatal irritation. A Strongylet affects the stomach, however, 



and they are found in the fourth 

 stomach and duodenum of Australian 

 sheep especially. The Palisade Worm 

 of the horse is a Strongyle, J and is 

 remarkable for the severe injuries it 

 does its host in its passage through the 

 tissues. According to Leuckart, they 

 pass into the body of an intermediate 

 bearer before entering the stomach of 

 the horse. From the alimentary canal 

 they pass through the tissues and enter 

 the blood-vessels, causing aneurism, and 

 thence they seek to regain the intes- 

 tinal canal, where they arrive at sexual 

 maturity. It is during their migratory 

 efforts that they give rise to dangerous 

 symptoms, not unfrequently causing the 

 death of yearling foals. 



One of the Nematoids allied to the 

 Strongyles has the male with a tail, 

 surrounded by a ring or crown of fine, lancet-shaped flaps connected together by a delicate web. 

 Probably these worms have something to do with hog cholera, a disease of the pork-producing- 

 districts of the United States. The gapes of fowls and other birds are produced by worms in the- 

 traohea or main air tubeil and the disease may be cured by careful operations. 



The so-called grouse disease depends on more than one worm parasite, one of which is a Strongyle.- 



STROXGYLUS PERGRACILIS. (After Cobbold.) 



A, Lead and neck : B, c, n, E, tail of male : p. tail of female ; o, section to show 

 termination of oviducts ; H, eggs. 



Stronyylus micrurus. 



Stephanurus dentatus. 



t Stronfii/Jus contortus. 

 Selerostoma syngamus. 



J Strongylus armatus. 

 ^ Strongykis pcrgracilis- 



