ORTHONECTIDJ; AND DICYEMIDJ] 



207 



order to seek a new host. In tlie body cavity of the latter, 

 again an Amphiura, their life-history is continued, but in a 

 different manner in the two forms. The flattened females 

 are said by Julin to break up into a number of fragments, 

 each one of which is composed of several central and peri- 

 pheral cells. These ciliated offspring develop into the 

 "plasmodial sacs" of Metschnikoff (No. 6). These are 

 sac-like structures, which consist of a granulated mass, and 

 exist in large numbers within the body cavity of Amphiura 

 and Nemertes. The centi^al cells contained in them are to be 

 considered as eggs, and 

 (in consequence of a 

 kind of parthenogenetic 

 reproduction) supply 

 both forms of females. 

 The mjlindrical females 

 while still in their new 

 host expel their central 

 cells — i.e., the eggs — and 

 these develop into in- 

 dividuals which differ 

 considerably in shape 

 from the females already 

 described. They are the 

 males of Bhopalura Giar- 

 dii, which, according to 

 Julin, are brought forth 

 by the cylindrical 

 females only. Whereas 

 the body of the female 

 is segmented externally 

 into nine rings, there are 

 only six rings in the male (Fig. 97 B). The second ring, 

 as in the females, is without cilia. The five rows of cells 

 which constitute it contain peculiar highly refractive bodies. 

 Within the animal there is differentiated an oval, sac-like 

 organ of a granular appearance. From it fine cords, which 

 are interpreted as muscle fibres, extend in the body forward 

 and backward. The organ itself corresponds to the testis ; 



Fig. 97. — A, cylindrical female; B, male 

 of Blwpalura Giardii (after Julin); H, testis ; 

 M, muscle fibres. 



