84 DEPARTMENT OF THE NAVAL SERVICE 



6 GEORGE V, A. 1916 



veying them from infected hosts to the water, the rapid contamination of fish, school- 

 ing densely like the herring, must follow, but such means do not seem to be directly 

 provided in all cases. For instance, one of the specimens had an opening on one side 

 of the caudal peduncle, the other had none. In the former case suppuration doubt- 

 less carried out swarms of sporonts to enter other hosts and spread the infection, but 

 many hosts seem to die in the progress of the disease before openings appear and 

 sloughing is possible. It does not seem that many are voided through the natural 

 openings, for their numbers in the intestinal tract, ovaries and spermaries are insig- 

 nificant when compared with the masses to be found elsewhere. It may be surmised 

 that the parasite has other hosts, and among them small organisms on which the 

 herring prey. It is only necessary to add that once the protozoan has entered a host 

 its wonderful power of rapid multiplication, absorption of the vital fluids and general 

 clogging and disordering of the vascular system, especially of the blood vessels, must 

 soon produce results highly lethal. 



Since the above was written, I received two lots of herring from Dr. Macallum : 

 lot No. 1, collected at Metis, P.Q., and lot No. 2, taken by Captain Wakeham at some 

 other point, the exact locality unknown to the writer. These fish were reported 

 diseased and dying. Indeed it seems as if a general epidemic was abroad among the 

 herring of the coast waters of Canada and Newfoundland during the spring, summer 

 and autumn of 1914. The first report came from Newfoundland, as the following 

 clipped from the St. John Globe, which was copied from the Eastport Sentinel, will 

 show : — 



" Enormous quantities of dead herring are being found in the waters surround- 

 ing Newfoundland, and fishermen are worried. Many look upon it as a plague, and 

 as the beginning of the end of the herring fishery, which, should it occur, means dire 

 poverty and distress in its very worst shape to thousands of people there." 



This was in April, and about the middle of June it appeared among the schools 

 along the New Brunswick shore. Later it seems to have become pretty general at 

 other places in the gulf. It is just possible that all these fish belonged to one great 

 migrating body. 



Lot No. 1 was made up of small fish from 6 to 8 inches in length and apparently 

 of the sea variety, being in all respects similar to the New Brunswick specimens. 

 The cause of death was the same in all cases. The parasite was especially abundant 

 in the coagulated blood of the heart and sinuses, the lateral line tissue was badly 

 affected or entirely destroyed, and sores were seen on the caudal peduncle, close to 

 the fin. 



Lot No. 2 was composed of larger and better conditioned fish, averaging from 

 11 to 12 inches in length. A few showed abrasions of the skin, apparently due to 

 chafing against stones when dead, but the tissue here seldom contained any parasite, 

 • except in the case of a very badly affected fish. Some had small sores in the axils of 

 the pectoral fins which seemed to open into diseased pockets where the contiguous 

 tissues literally swarmed with parasites, generally in the sporont stage. The extra 

 flow of blood to these parts may account for the colonies. A few axillary sores, how- 

 ever, seemed due to some external parasite, probably a crustacean, for the protozoan 

 did not occur in the neighbouring tissue. In one, a well-conditioned and preserved 

 specimen, no parasites were found, and the cause of death was probably due to an 

 accident. 



No Neosporidia were found in the brain, and the larger and least contaminated 

 fish showed an immense number of plasmodia or multinucleate cells, see figs. 11-14, 

 which seem to be characteristic of the initial, as the sporonts are of the final stages 

 of the disease. 



