6i8 



CESTOIDEA 



The geographical distribution is interesting, it being mostly found in South 

 Germany, Switzerland, the Austrian Alpine region, Russia, and East Siberia, 

 in which districts it occurs in large cattle and man, whereas it is absent from 

 Iceland and Australia and European districts where sheep are common and 

 where the other form is frequently met with. 



Morphology. — Melnikow-Raswedenkow says that the cysts are composed 

 of parenchyma internally and externally, the latter being in direct contact 

 with the tissue of the host, and producing, it is said, not merely scolices, but 

 immature amoeboid embryos, which spread the cyst by continuity, or may 

 enter the blood-stream and form metastases. 



An amoeboid embryo develops into a much-folded chitinous vesicle, having 

 parenchyma both internally and externally. This parenchyma produces 

 poisons which act upon the host. The cyst is looked upon as the homologue. 

 of a ripe proglottis, because it can produce living embryos, for the parenchyma 

 can form scolices, immature embryos without a capsule, and mature ovoid 

 embryos enclosed in a chitinous capsule. 



The scolices, however, are frequently destroyed by phagocytosis, because 

 they are situated in direct contact with the host's tissue. Hence the failure 

 of feeding experiments, as the scolices arrive in the intestine damaged. 



The result of this development is to produce a collection of cysts, measuring 

 from o-i to 5 millimetres in diameter, embedded in connective tissue. Dis- 

 integration may begin in the centre of the masses of the cysts. Whether the 

 TcBnicB obtained by feeding experiments are the same as T. echinococcus or 

 not is uncertain. 



Pathogenicity. — It produces a primary tumour in the liver, brain, spleen, 

 kidney, or adrenals, with metastases in different parts of the body. The 

 symptoms produced vary with the region affected, but eventually, perhaps 

 after years, lead to anaemia, emaciation, and weakness, which cause death. 



REFERENCES. 



The most useful general reference is ' Die Susswasserfauna Deutschlands 

 eine Exkursionsf auna, ' Heft i8. Parasitische Plattwiirmer. II. Cestodes. 

 Fischer, Jena, 1910. 



General. 



Blanchard (1889). Traite de Zoologie Medicale. Paris, I. 



Braun (i 894-1 900). Bronn's Thierreich, vol. iv., ab i b. Leipzig. (This 



gives a full literature up to 1895.) 

 Braun (1908). Die thierischen Parasiten des Menschen, 4th ed. Wiirzburg. 

 Leuckart (1886). Parasites of Man. English translation. Edinburgh. 

 Looss (1905). Mense's Handbuch d. Tropenkrankheiten, vol. i. 

 Stiles (1906). Bull. 25, Hyg. Lab., U.S. Pub. Health and Mar. Hosp. Serv. 



(Key and specific diagnosis of tapeworms of man.) 

 Ward (1903). Studies for the Zoological Laboratory University, Iv. 49. 



Nebraska, also No. J4 of 1902. 



Dibothriocephalus latus. 



Stiles (1906). Loc.cit. 



Ward (1901). Circulars on Tropical Diseases, i. 22. 



Dibothriocephalus cordatus. 



Leuckart (1886). Loc. cit. 



Diplogonoporus grandis. 



Stiles and Tailor. Bull. 29, U.S. Bureau Animal Industry. 



Diplogonoporus brauni. 



Leon, N. (1907). Zoologischer Anzeiger, xxxii. 376. 

 Leon, N. (1908). Ihid. 



