
AILMENTS AND DISEASES 

Myxosporipia. The freshwater fish-parasites of this order belong 
to the genera Myxidium, Myxobolus, Henneguya, Nosema and Plistopora. 
Myxosporip#&. These Protozoa, Figs. 102,1024,103, 104 and 1044, 
are entirely parasitic and in the majority of cases live upon fishes. Dr. R. 
R. Gurly listed 102 hosts, fishes and other aquatic fauna, inhabited by them, 
either éntysted beneath the skin, on the surface of the head and fins, or in 
the gills, mouth, eyes, gullet, air bladder, heart, liver, spleen, stomach, in- 
testines and almost every other part of the body. The effect of their presence 
is a breaking up of the parts, which undergo a vitreous degeneration, the 
growth of tumors and postules and ultimately the death of the host. 
FIG. 103. My.xobolus cyprini, a Spora- 
xoan parasite, encysted in the Kidneys of a 
Carp. 1. Enlarged 2. Natural size of cysts. 

FIG. 104. Myxobolus ellipsoides, a Sporozoan 
parasite. Greatly enlarged. 
I 2 1. Cyst in the tissues of the Air-bladder of a 
Tench. 
2. Psorospores liberated from the cyst, highly 
magnified. 
They are usually amceba-like microscopic organisms, which reproduce with- 
in or without the cyst or tissue cavity with those species which inhabit the 
surface; and constantly within the cyst with those which inhabit the cavities 
of the hollow organs of their hosts. Mention will only be made of those 
Myxosporide of the orders Phenocystida and Microsporidiida common to 


FIG. 104a. Dermal cysts of Myxosportdium genys incert, a Sporozoan 
parasite, on the skin of a Minnow. 2. Liberated psorospores, highly magnified. 
freshwater fishes, batracians and larger crustaceans, the table showing how 
many species have been identified and the parts they inhabit. It is seldom 
that they have more than one particular host; that of the goldfish, for 
instance, being Myxobolus sp. incert, Figs. 102 and 1024, and Table p. 156. 
Myxosporide spare no organ or elemental cell and nearly all of them 
produce a cachexia, comparable with the cancerous tumors of warm-blooded 
animals. ‘They are the cause of violent epidemics among fishes and have 
occasioned the deaths of hundreds of tons of food fishes in a very short 
time when outbreaks of the contagious diseases caused by them have 
155 
