FISH PESTS 239 



so engaged it is not inactive, but is capable of 

 moving by pseudopodia over the surface of the 

 cavity containing it, or in and between the cells by 

 which it may be surrounded. Parasites lying in the 

 gall or urinary bladders of fishes form temporary 

 attachments for themselves by means of their pseudo- 

 podia, and there is no doubt that these pseudopodia 

 are not merely organs of attachment, but also are 

 organs of absorption. We, ourselves, have seen food 

 currents from invaded cells pass into the pseudo- 

 podia, and when sections of the infected gall-bladders 

 of certain fishes such as the pollack are examined, 

 the great deformity of the cells is evidence of the 

 action of the parasites. 



When tissues are infected, softening sometimes 

 occurs ; at others, hard lumps form beneath the skin. 

 One kind of Myxosporidia infests the gills of certain 

 fishes, where it forms hard lumps that interfere con- 

 siderably with the aeration of the gills. Another 

 member of the group produces excrescences on the 

 nerve roots of its host. Yet another invades and 

 liquefies the muscles of a large, pikelike fish used 

 extensively for food in Australia, especially in New 

 South Wales and Queensland. The infected fish are, 

 however, sold in the open market, and the poorer 

 members of the community suffer, as " milky Barra- 

 coutta," or " Barracuda," is avoided by all who can 

 afford to do so. The exudate from the disorganized 

 musculature of the fish resembles milk, and owes its 

 colour to the numbers of myxosporidian spores 

 present in it. The special organism in this case is 

 known to be a Chloromyxum. 



