354 ULCER DISEASE OF RAINBOW TROUT, 



operation the fishes were put into metal tubs, fed with a stream 

 of fresh water from an o^^erhead tap, and the tubs were protected 

 by nets placed over them. The trout were left in charge of the 

 caretaker, who had instructions to forward at once to Sydney the 

 carcases of any fish that might die, as delay in doing so might 

 seriously influence the investigation. 



On the sixth day after inoculation one of the trout died, and 

 the carcase was received at the laboratory. The caretaker had 

 noted that it had been sickly on the previous two or three days. 

 The carcase had no epidermal lesions, and on dissection the 

 organs were found to be healthy. The blood vessels of the 

 stomach, intestine and milt were, however, much congested, and 

 the muscle at the point of inoculation was soft and haemorrhagic. 

 In the bacteriological examination, Micrococcus pyogenes was 

 obtained from the muscle at the site of inoculation, from the 

 spleen and from the kidne}^ The muscle on the reverse side and 

 the heart blood were sterile. Two fishes died on the ninth day, 

 a Saturday, but owing to a misunderstanding regarding the 

 necessity of a speedy despatch and the arrival at the laboratory 

 on Sunday, the carcases were not sent. A fourth trout, which 

 had developed a w^hite mark on the head, somehow eluded the 

 protecting net and got out of the vessel. The caretaker noted 

 that after death the mark had almost disappeared. It was 

 unfortunate that this carcase was not despatched to me. A 

 fifth fish died eight weeks after the inoculation with the external 

 lesions of ophthalmia — viz., one of the eyes had decayed — only 

 the capsule remained. The epidermis of the head and tail had 

 whitened in places, but no ulcers had formed on the body. Upon 

 dissection the organs were seen to be healthy, but there was a 

 considerable congestion in the blood vessels of the intestine and 

 body cavity. The organs, and especially the milt, were stained a 

 deep orange-yellow by the bile. Like the fishes that died after 

 natural infection, the body lesions of this experimental fish were 

 not pronounced. The juices of the various organs, the blood and 

 portions of the brain were examined bacteriologically, and while 

 putrefactive bacteria were found, Micrococcus pyogenes could 



