402 ON A PROTOZOAN BLOOD PARASITE OF THE SEA-rROUT. { Apr. 6, 
the heart. The liver and the submucosa of the stomach and the 
intestine were very strongly infected, far more so than any of the 
organs from the trout. This material gave a more complete 
picture of the trophic life of the parasite. Such points as the 
multiplication of the nuclei, the exit from the envelope, and the 
breaking up of the large individuals into numerous small naked 
bodies with few nuclei were clearly illustrated in the sections. 
There were, however, nosigns of sporogony. In the flounder very 
large connective-tissue cysts were formed both in the liver and in 
the alimentary canal. The only difference between the infection 
in the sea-trout and that in the flounder is in the greater 
development of connective tissue on the part of the latter host. 
The flounder in question must ultimately, I should think, have 
succumbed to the disease, as the liver was in a very pathological 
condition, but it had been living for some months in captivity 
in the tanks of the Millport Marine Station and showed no 
external sign of ill-health. 
From the material at my disposal only a very incomplete 
account of the Ichthyosporidium can be given. It is to be hoped 
that this form, which is interesting both from a purely scientific 
as well as an economic point of view, will receive further attention 
from Protozoologists and will be studied under more favourable 
conditions. 
Since writing the above paper another case of the occurrence of 
this disease has come under my notice in haddocks from Aberdeen. 
A fishmonger in Glasgow, while cutting the fish into fillets, 
observed minute yellowish white granules in the tissues. He 
sent the fillets to Prof. Graham Kerr, who forwarded them to 
me at the Lister Institute. It was found that the appearance 
was due to the presence of an immense number of an Ichthyo- 
sporidian apparently identical with the one described in this 
paper. 
EXPLANATION OF PLATES LXII-LXIV. 
Ichthyosporidians of Sea-Trout. 
Fig. 1. Magn. of 35 diam. Showing general appearance of the parasites in section 
of the heart. 
Magn. of 100 diam. General view of the parasites, showing different shapes 
assumed. 
Magn. of 250 diam. Single large parasite, showing the envelope. 
Magn. of 250 diam. Single large parasite; the ‘Shrinkage is due to the 
fixation, as also the appearance of the nuclei at one side. The envelope 
shows clearly. 
5. Magn. of 500 diam. Shows thin layer of connective tissue round the 
arasite; envelope of the Ichthyosporidiwn and the nuclei are both shown. 
Figs. 6 & 7. Magn. of 1000 diam. These two ficures show the nuclei; the fine rays 
passing from the karyosome to the membrane can be seen. 
Fig. 8. Magn of 1000 diam. Shows the nuclei distorted in the process of fixing. 
9. Magn. of 750 diam. Gives another appearance caused by fixation. 
bo 
These figures are from untouched photographs kindly executed by Dr. Reid. 
