126 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
only by careful attention to the individual fish as fast as they showed 
the slightest signs of being affected. Nothing proved to have decided 
advantages over the use of salt for this purpose. A permanganate of 
potash solution, reported as almost a specific for fungus in England, 
was a failure. It could not be introduced into the water continually 
on account of the color imparted, and especially because the fish 
would not endure, save for a comparatively short time, even a very 
weak solution. The short dip in stronger solutions was impracti- 
cable, as there was no safe margin between a strength of solution 
which was fatal to the fungus and harmless to the fish. Formalin 
was expected to give better results, but according to the report of the 
superintendent of the exhibit did not do so, and at best nothing would 
improve very much upon salt, for there remains in any case the neces- 
sity of attention to the individual. Salt is moderately successful as a 
remedy when the attack has not proceeded very far. 
Some bacteriological work was undertaken in connection with the 
Lynn Haven experimental oyster claire. The so-called ‘‘ muddy” taste 
of oysters from this claire can not be attributed to bacterial infection 
or pollution, although the colon bacillus was obtained from the stomach 
of some oysters. It was not obtained, after test for it, from the claire 
water or fertilizer, and its presence in the oysters is not constant. Ob- 
servations are too few to show the significance of its presence in the 
few cases recorded. 
Mr. Marsh devoted the last half of the year chiefly to work in the 
bacteriological and pathological laboratories of Johns Hopkins Uni- 
versity, where an exhibit of bacteria related to fishes and fish diseases 
was arranged for the Commission’s display at the Pan-American Expo- 
sition. Over twenty species were prepared, each represented by a 
plate culture and two tube cultures. They consisted of water bac- 
teria, the pus cocci, bacteria obtained from diseased fishes, a chromo- 
gen from the disease known as ‘‘ pop-eye,” a phosphorescent bacillus, 
and the bacillus of tuberculosis in fishes. The cultures were usually 
killed and the medium hardened by formalin, and the tube or plate 
sealed with paraffin. 
The necessity for carrying on microscopic and bacteriological work 
in the field led to the preparation of an outfit to serve as a portable 
laboratory. The extensive traveling outfit of the Marine-Hospital 
Service furnished a precedent and in a general way a model for the 
plans of a similar but much smaller one adapted to the needs of the 
Commission. It consists of the smallest quantities of apparatus and 
material consistent with usefulness and efficiency for performing the 
more ordinary bacteriological and microscopic manipulation, execlu- 
sive of incubation at body temperature and anaérobic culture. The 
essential idea in the gathering together of the apparatus as a unit was 
to do work which could be done only in the field, and which was to be 
continued in a more complete and permanent laboratory. 
The bacteriological researches of the Fish Commission were greatly 
