208 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



and characterised by lack of co-ordination in the swim- 

 ming movements of the animal. It lasts for some weeks 

 and usually leads to the death of the fish. Hofer found* 

 that various organs in the animal were infected by an 

 organism which he regarded, provisionally, as a 

 sporozoan. They were contained in rounded or Oval 

 cysts, many of which showed proliferation, or vegetative 

 growth. Plehn and Mulsow were successful in isolating 

 these bodies and cultivating them in artificial media, 

 when a typical mycelial growth was produced. The 

 appearance of this is represented in their figures. They 

 were able to show that it was a Phycomycete fungus 

 belonging to the group Chytridinae, and they called it 

 Ichthyophonus Hoferi. Now I think there can be no 

 doubt that the parasite here described from the mackerel 

 is very closely allied to the species of Plehn and Mulsow, 

 if it is not identical, but in the absence of fresh material 

 capable of setting up cultures it is, of course, impossible 

 to be certain, and I hesitate to make the identification. 



A closely similar condition was described by me in 

 1905. t Plaice living in captivity in the spawning pond 

 at Port Erin Fish Hatchery became subject to an 

 epidemic disease, characterised by extensive ulceration 

 and death of the fish. Some of these fish examined by 

 me proved to be infected by a fungus which I identified 

 as a genus of Entomophthorineae, near to the form 

 Conidioholus. The appearance of the organism in these 

 plaice was rather different from that written about here. 

 A mycelium was established in the liver, and this growth 

 was much more massive than that found in Mr. Scott's 

 mackerel. I attributed the disease and death of these 



* Hofer, Handbuch der Fischkrankheiten. Stuttgart, 1906, pp. 286- 

 289, Text-figs. 177-181. 



| Johnstone, " Internal parasites and diseased conditions of fishes." 

 Ann. Bept. Lancashire Sea Fisheries Laboratory for 1905. In Trans. 

 Liverpool Biol. Soc, Vol. XX, 1906, pp. 295-329, PI. XVI., figs. 3-7. 



