1909.] ON A PROTOZOAN BLOOD-PARASITE OF THE SEA-TROUT. 399 
2. Notes on an Ichthyosporidian causing a I’atal Disease in 
Sea-Trout. By Muriet Ropertson, Carnegie Research 
Fellow *. 
[Received March 1, 1909.] 
(Plates LXII—LXIV.7) 
In July 1907 Dr. Turnbull, of the London Hospital Medical 
School, while fishing on the River Ewe in Ross-shire, observed 
that a number of sea-trout were affected with a disease which cul- 
minated in the death of the fish. Externally they showed nothing 
abnormal, but on opening them he found that the heart, liver, 
spleen, and pyloric ceca showed minute sand-like granules. 
Dr. Turnbull’s description of a typical infection reads as 
follows :— 
“The gills were healthy and showed no adherent parasites. 
“The heart: the ventricle was pale, rough and sandy, and 
minute white granules could be seen. Similar granules were on 
the auricles and sinus venosus. 
“ The liver was of a yellow colour and showed minute, yellowish- 
white, slightly raised, rounded granules on the surface and in 
section. 
“‘Tn the spleen very few granules could be detected. 
“ The alimentary tract was empty and no duodenal tape-worms 
were present. 
“The brain, on removal, showed no abnormalities. 
“¢The ovaries showed no granules.” 
Some fish, however, showed an even more complete infection 
than this; thus in some cases the pyloric ceca, the gills, the 
submucosa of the csophagus, the testicles, and the parietal 
muscles beneath the peritoneum all showed the characteristic 
sanded appearance. 
Dr. Turnbull observed that the diseased sea-trout were all 
fresh-run fish and were generally of about 4 lbs. weight and over, 
although one infected fish was got which weighed 2 lbs. 
The River Ewe runs from “‘ Loch Maree” into the sea-loch 
“Loch Ewe” at “ Poolewe.” It is a short river, only about a 
mile and half long. 
The various internal organs of some of the infected fish were 
preserved in methylated spirit, this bemg the only preserving- 
fluid obtainable. Sections were made which were sent along with 
Dr. Turnbull’s notes to Prof. Minchin at the Lister Institute. 
The disease proved to be caused by a Protozoan parasite belonging 
to the genus Jchthyosporidium. 
In January 1909 Prof. Minchin handed over to me the 
material together with his own and Dr. Turnbull’s notes, and it 
* Communicated by Prof. E. A. Mrncurn, M.A., V.P.Z.S. 
+ For explanation of the Plates see page 402. 
