464 Tapt'wunns. 



infections, and inflammatory processes following upon tliem, 

 and also the poisonous jDroducts of worms are undoubtedly re- 

 sponsible for nervous s>^nptoms, such as excitement, convul- 

 sions and paralysis, which are sometimes seen, and are then 

 due to reflex irritation. 



The intensity of the morbid condition varies according- to 

 the species and number of intestinal parasites and also accord- 

 ing to the individual irritability of the affected animals. The 

 larger worms, and particularly those provided with hooks, are 

 generally more dangerous, but even small worms, when present 

 in large numbers (for instance Taenia, echinococcus, Dochmius 

 trigonocephalus), may also cause serious disease. Both, differ- 

 ent species and ditferent individuals of the same species, show 

 great varial)ility as to irritability; this is most markedly shown 

 in dogs. These factors and the resistance of the worms to an- 

 thelmintics are important for the significance and prognosis of 

 the affections caused by intestinal parasites. The latter, Avhich 

 occurs in domestic animals, are tapeworms (Plathelminthes: 

 Cestodes, Trematodes) and roundworms (Nemathelminthes: 

 Nematodes, Acanthocephala). 



Literature. Linstow, Kongr., Budapest, 1905, I, 387 (Lit.).— V. Eatz, VII, 

 Intern, hygieu. and demogr. Kongress, 1894 (Lit.). 



A. Tapeworms. Cestodes. 



Tapeworms are bandlike colonies of hermaphroditic indi- 

 viduals arranged in adhering segiiients. The anterior segments 

 of each animal, or animal colony, forms the socalled head (sco- 

 lex) ; it is to be looked upon as the mother of the colony which 

 continually forms new segments asexually, by longitudinal 

 growth and transverse segmentation, that is, individuals which 

 do not become separated, but adhere to each other. The more 

 distant the segments are from the scolex, the larger, wider and 

 longer do they get. Those situated caudally show more dis- 

 tinctly the sexual organs, which attain their full development 

 in the last segments of the band (strobila). The mature seg- 

 ments are also called proglottides. The individual seginents 

 are hermaphroditic ; the uterus usually contains numerous eggs, 

 and it shines through the external layer of the proglottides; 

 its characteristic shape may be utilized for determining the 

 species. The sexual openings or pores are on the margin of 

 the individual segments in Taenidae, and on the flat surface in 

 Bothriocephalidae. 



The segments are formed by a doul)le layer of connective 

 tissue; the external layer contains small granules of lime. The 

 nutritive material of the intestinal contents of the host pene- 

 trate into the body of the worm through small openings of the 

 segments. The excretory products of the worm are voided 

 through a system of canaliculi contained in the lateral portions 



