BY R. GREIU SMITH. 355 



neither be detected nor isolated. This is precisely what occurred 

 with the fishes that succumbed naturally to the disease. It was 

 only from those trout which had body sores that the micrococcus 

 could be obtained. The sixth experimental trout was alive and 

 apparently healthy at the time of writing. 



In reviewing the infection experiment, it is seen that one was 

 lost, thus reducing the number to five. Three of the five succumbed 

 about the same time, and since the inoculated bacterium was 

 recovered from one, it is probable that had the others been sent 

 to the laboratory the organism would also have been recovered 

 from them. The fourth developed ophthalmia and died, while 

 the fifth was apparently unaffected by the inoculation. 



Since the infected micrococcus could not be separated from the 

 trout that succumbed with the lesion of ophthalmia, it is possible 

 that the fish might have died quite independently of the inocula- 

 tion. On enquiry, I was informed by Mr. Brodie that about 

 three trout had died weekly from ophthalmia since the time of 

 the inoculation, and that epidermal sores had never been observed 

 after the height of the disease. As the tanks were carrying about 

 400 fishes, this means a death rate of 1 in 20 during the period 

 that elapsed between the time of inoculation and the death of the 

 fourth experimental fish. 



So far as the infection experiments go, the micrococcus was 

 pathogenic, although it did not produce lesions similar to those 

 from which it was isolated. This can be explained by the 

 experimental fishes being in more healthy surroundings. Had 

 the water been as unhealthy as that in the tanks during the 

 height of the disease, it is probable that the ulcers would have 

 developed. Among mammals the same micrococcus produces 

 sores when the vitality of the animal is lowered by some cause, 

 and since it obtains among the higher animals, there is no reason 

 wh}^ it should not also hold among fishes. Another point to be 

 remembered is that by the time a constant flow of water could 

 be depended upon at the hatchery about two months had passed, 

 and during this time the bacterium may have lost in part its 



