EURYSPOREA. 333 



tubules of the kidney or urinary bladder, and do not cause 

 much harm to the host. In other cases the parasites invade 

 the tissues, causing them to degenerate, and give rise to 

 tumours in muscles, central nervous system, etc., which are 

 referred to as Myxosporidian cysts and are visible to the naked 

 eye, or the parasites may spread through tissue, giving rise to 

 diffuse infiltration. 



TheMYXOSPORiDiA are parasites of cold-blooded Vertebrates, 

 more particularly fishes. Each species attacks one or several 

 species of fish. In the case of freshwater fishes they usually 

 invade the gills and the gall-bladder, while in the marine 

 fishes they are usually found in the gall-bladder or the urinary 

 bladder. Whitish pustules visible to the naked eye may 

 indicate the infection in the giUs, and in the case of internal 

 organs there may be abnormal changes of form or colour, 

 but ordinarily infection can only be detected by microscopical 

 examination. 



Doflein (1901) divided the order into two suborders, Dis- 

 POREA and PoLYSPOREA, but Kudo (1920) considers such 

 a division an artificial one, as the number of spores produced 

 by any species is not always constant. 



Following Kudo (1920, 1933) the Myxosporidia are divided 

 into three suborders, as follows . — 



1. Largest diameter of the spore at right angles to the 



sutural plane ; one polar capsule on each side of 



the plane ; sporoplasm without iodinophilous [Kudo, p. 333. 



vacuole Eurysporea, 



2. Spore spherical or subspherical, with one, two 



or four polar capsules ; sporoplasm without [Kudo, p. 335. 

 iodinophilous vacuole SphaBFOSporea, 



3. Sutm-al plane of the spore coincides or forms 



an acute angle with the longest diameter ; one 



or two polar capsules ; sporoplasm with or [Kudo, p. 336. 



without an iodinophilous vacuole Platysporea, 



I. Suborder EURYSPOREA Kudo, 1920. 



The largest diameter of the spore is at right angles to the 

 sutural plane, with one polar capsule on each side of the plane. 

 Sporoplasm without iodinophilous vacuole. Vegetative form 

 found in body- cavity. The great majority are parasites of 

 marine Fish. Monosporous, disporous or polysporous. 



Identification Table of Families. 



i. Typically coelozoic, in marine Fish . . Ceratomyxidse Doflein, p. 334. 

 2. Histozoic or coelozoic, in fresh- 

 water Fish Wardiidse * Kudo. 



