BARBEL DISEASE 



253 



variegatus of North America, chalky secretions occur 

 intermingled with the spores. 



The barbel disease is due to Myxobolus pfeifferi. 

 The external features consist of discoloured patches 

 on the skin, and large, lumpy tumours sometimes 

 reaching the size of a fowl's egg. The parasite has 

 small trophozoites which may confine themselves to 

 the kidney tubules of the barbel, or may diffuse 

 throughout the 

 connective tissue 

 of the kidney, liver, 

 spleen, and muscu- 

 lature. Even the 

 genital organs may 

 become heavily 

 charged with para- 

 sites. No part 

 seems absolutely 

 immune. When 

 the parasites lie 

 between the muscle 

 fibres, the tissue 

 endeavours to shut 



off the parasite, and great thickening occurs in 

 its neighbourhood, so that a structure resembling 

 a worm cyst is produced. Within this capsule the 

 trophozoite develops an enormous number of spores, 

 and finally perishes, leaving its own degenerated 

 body and the degeneration products of its activity, 

 together with the spores to fill the space it originally 

 occupied. 



The spores are very small egg-shaped bodies with 



FIG. 48 SPORES OF A MYXOBOLUS FROM 

 A MUSCLE FIBRE OF THE BARBEL : 

 TRANSVERSE SECTION 



