PREFACE. IX 



in Actinophrys Eichhoryin, where it lies close to the surface. See 

 Clapaeede Ueher Actinophrys Eichliornii in Mueller's Archw, 

 1854, pp. 398—419. 



No notice was taken by the translator of an order of minute 

 parasites, the Gregarince, wliich may be most naturally arranged 

 amongst the Infusories after the RMzopoda. They were discovered 

 by Leon Dufour in the intestine of insects [Forficula^ Melasoma, 

 &c.), and were so named by him on account of their congregating 

 in numbers. They are of various form, round, oval, elongate; con- 

 sist of an external, structureless, elastic membrane, and a fluid 

 content in which innumerable granules of various form and size 

 are embedded, whilst within the granular mass a circumscribed 

 body with one or more opaque spots, the so-called nucleus, is found. 

 There is neither mouth nor vent. 



There are two families of Gregarinoe: 1, Motwcystidce of Stein, 

 where the animals are solitary ; 2, ZygocystidcB, where two indivi- 

 duals are conjoined. The Monocystidm have for their type the 

 simple animals found abundantly in the space between the skin 

 and the intestine in the earth-worm and in the testes. The Zygocy- 

 stidce contain two genera: 1, Gregarina Leon Dufour; 2, Sty- 

 lorliynclius Stein, Avitli a proboscis which is sometimes surrounded 

 by a circle of booklets. 



Stein believed that the Gregarince are propagated by the con- 

 jugation of two individuals which become included in a common 

 cyst. From this intimate union arise spores {Pseudotmmcelloe, 

 Spindle-cells, Psorosperonice) , which after a time allow new indivi- 

 duals to escape. But although two individuals are often thus 

 included in the same cyst, a process like that of the conjugation 

 of cryptogamous plants does not occur, for the psorosperms are 

 equally produced when only a single Gregarina is encysted. The 

 process begins with the disappearance of the nucleus, and consists 

 of many stages, according to N. Lieberkuehn {Evolution des Gre- 

 garines in Mem. couronnes des Sav. Etrang., Acad. Roy. d^ Brux- 

 elles, 1855). This author concludes from his observations that 

 instead of the Gregarince escaping directly from the shell of 

 the Psorosjyerms, Amoehce are the product, and that finally these 

 AmoehcB are transformed into Gregarince. All the successive stages 

 are to be seen in the testes and abdominal cavity of the Earth- 

 worm, where chiefly they were studied by Lieberkuehn. 



VOL. IT. h 



