GENERAL ORGANIZATION 



The behaviour of the spores after ingestion by a 



721 



new host has been 

 studied by several observers, whose accounts are by no means concordant. 

 In the case of M. bergense, a parasite of the gall bladder of the saithe, 

 Gadus virens, Auerbach (1910) noted that after entering the duodenum of 

 the fish the polar filaments of the spore were extruded and the two valves 

 of the spore capsule separated. This allowed the binucleate amoeboid 

 body to escape. The two nuclei then fused, and the resulting uninucleate 

 amoeboid body made its way to the bile ducts, into one of the cells of which 



B 



r #6^1?®®^'^^:^! 



Fig. 306. 



My.robolas pfeifferi in the Tissues of the Barbel. (After 

 Thelohan, 1894.) 



A. Portion of intestinal wall of the barbel infected with 2Iif.roholiis pfeifferi. 



B. Connective tissue of kidney of barbel infiltrated with Mi/xnhnJus pfeifferi. 



C. Portion of the fibrous tissue shown in A more highly niagnitied. 



T>. Muscle fibre of the barbel infected and destroyed by Myxohohis pfeifferi. Spores 14 x 10 /i. 



it entered. Later it is described as leaving the cell and multiplying by 

 binary fission in the lumen of the bile ducts or gall bladder. The uni- 

 nucleate amoeboid forms then associate in pairs, while the nucleus of one 

 of each pair divides to form two nuclei, one of which is discharged from the 

 cytoplasm. The two cells, one of which has a reduced nucleus, now unite 

 to form a binucleate mass with one large and one small nucleus. Other 

 observers, as, for example, Davis (1916), Georgewitch (1917), Erdmann 

 (1917), Schuurmans-Stekhoven (1919), and Kudo (1922), working with 

 other species, maintain that such a union does not take place, and that 

 I. 46 



