FISH "STAGGERS" 255 



with their bodies and spores. Some of the tubules 

 retain the power of excreting sufficient liquid to wash 

 out some of the spores, which find their way then 

 into the excrement and mingle with the faeces, 

 whence spores can be recovered. As the number of 

 spores is very great, and as each trophozoite pro- 

 duced therefrom has enormous potentialities of 

 further spore production, one diseased fish can 

 easily infect a considerable area of water by means 

 of its evacuations, while the decay of one dead carp 

 means the release of innumerable spores in a short 

 time. A certain amount of discussion has arisen as 

 to whether or no Myxobolus cyprini is the true cause 

 of the carp disease. But while other agencies have 

 been suggested, nothing has been proved except that 

 Myxobolus cyprini can cause the skin disease and 

 death of the host. The idea that M. cyprini was not 

 deadly arose partly from the view that many of the 

 Myxosporidia were non-pathogenic, and analogy was 

 used instead of fact. Another Myxobolus occurs in 

 the nerves and spinal cord of brook-trout, to which 

 it causes injury. 



The second genus of the Myxobolidae is the Lento- 

 spora, members of which are responsible for deform- 

 ities in the skeleton of certain Salmonidae and the 

 cartilaginous parts of such fishes as the cod and 

 whiting. The balancing organs, which form part of 

 the ear, may become infected, with the result that 

 the fish cannot maintain their equilibrium. In fact, 

 they may be said to suffer from "fish staggers." 

 The cartilaginous parts of the skeleton are attacked 

 chiefly, but as the membranes that nourish the 



