112 THE ANIMAL PARASITES OF MAN 



The species of Thelohania that occur in the muscular system of river 

 craw-fish and Palaemonidae are likewise capable of causing diseases, which, 

 however, have nothing to do with typical craw-fish plague, as the latter 

 is decidedly and solely caused by the Bacillus pestis astaci, Hofer. 



Four genera are now distinguished in the Microsporidia : Thelohania, 

 Henneg., Nosema n&gali ( Glugea, Thel.), Plistophora, Gurley, and Gurleya 

 Dofl. 1 



Order 6. Sarcosporidia, Balbiani. 



This group, which is the one that has been least studied, was first 

 discovered by Miescher (i) in 1843. This author found milk-white fila- 

 ments running parallel with the direction of the fibres in the voluntary 

 muscles of domestic mice ; they were visible to the naked eye, and proved 

 to be cylindrical tubes rounded off and tapering at each end ; they were 

 as long as the muscular fibres, were enveloped in a membrane, and con- 

 tained innumerable elongated or kidney-shaped bodies and a smaller 

 number of little globular forms. J. Hessling (2) confirmed the occurrence 

 of these " Miescher's tubes " within the muscular fibres, this author having 

 discovered the same formation in the miocardium of deer, cattle and 

 sheep. Both investigators considered them to be pathological transforma- 

 tions of the muscles, v. Siebold (3), from his own experiences, regarded 

 them as fungus-like entophytes. 



Rainey (4) discovered similar formations in the muscular system of domestic 

 pigs, and proclaimed them to be early stages of the Cysticercus cellulose, 

 which error Leuckart (5) rectified, simultaneously emphasising their rela- 

 tionship with Myxosporidia. Both these authors found them in the mus- 

 cular fibres and both observed that they possessed a thick striated mem- 

 brane. Manz (6) published the results of more minute investigations 

 on the structure and contents of the cylinders. This observer also 

 recognised the disease in rabbits and attempted to cultivate the parasites ; 

 he also tried to induce experimental infection in guinea-pigs, rats and 

 mice, but the result was negative. 



However domestic and wild, mammals are not the only hosts of 

 Sarcosporidia ; these parasites are also harboured by birds. Thus, according 

 to Kiihn (7) they are found in the domestic fowl, according to Rivolta (8) in 

 Turdus Corvus and other birds ; according to Stiles (9) in North American 

 birds. Neither do the reptiles escape. Bertram (10) found them in the gecko, 

 Liihe (i i) in the wall-lizard. It also became evident that the Sarcosporidia 

 found conditions suitable to their development not only in the muscles but 

 also in the connective tissue. This led to the foundation of a new classification 

 [Blanchard (12)]. Finally, Sarcosporidia have also been observed in man. 



The relation of these parasites to certain diseases of domestic animals 

 has been especially studied by veterinary surgeons (13). 



But little that is fresh (14) has been added to the results of the 

 work of Bertram (10) mentioned above, and on which the following 



1 The recent literature of the myxosporidia also contains information respecting 

 the microsporidia (Gurley, Thelohan, Doflein, &c. ; see also Labbe, Sporozoa, 1899). 



