OBSERVATIONS ON SAPKOL.EGNIA INFESTING FISHES, 165 



skin, as the Mississippi catfish, or with a development of prickly and bony plates like 

 the sturgeon, were usually free from the disease, while such as sunfish and black bass 

 were quite badly affected. Certain species, as the goldfish, which have been reported 

 in other places as sometimes becoming infected, escaped here, giving no evidenceof the 

 disease. It is also a fact that all those foreign fish that were bred by the Fish Commis- 

 sion, and that are commonly cultivated as aquarium fish, such as the goldfish, already 

 mentioned, golden ide, and tench, escaped entirely, while native fish recently collected 

 from streams, etc., were quite apt to become infected unless well provided with resist- 

 ing epidermal parts. Daily examination of the aquaria during a period of three 

 weeks showed that at that time sturgeon, burbot, mud catfish, Mississippi catfish, carp 

 (American, scale, mirror, and leather), tench, goldfish, golden ide, young trout (brook, 

 Von Behr, and Loch Leven), and young black bass were practically free from attack ; that 

 small-mouthed black bass, rock-bass, brook trout (adults), yellow catfish, spotted catfish, 

 buffalo, dogfish, paddle-fish, moon-eye, the long-nosed and short-nosed gar, the red- 

 horse, and the common suckers were somewhat affected, often but slightly and usu- 

 ally in bruised places; and that the black bass (adult), white bass, yellow bass, calico 

 bass, yellow perch, grayling, pike, pike perch, sheepshead, sand pike, bream, blue sun- 

 fish, warmouth, and individual cases of the sucker and redhorse were badly diseased. 



It has long been known that dead insects falling into water are quite likely to have 

 developed on them a growth of the species of fungi under discussion,* and botanists 

 have taken advantage of this fact for the development of these fungi, placing insects 

 in water likely to contain such forms, or inoculating inseots and then placing them in 

 pure water. In such cases, in a few days, a vigorous growth of fungous filaments 

 radiates from the insect on all sides, and the appearance and development of the 

 fungus can be studied as desired. The only drawback to such cultures is that bac- 

 teria are likely to develop on the dead insect, and after a time seriously interfere with 

 the growth of the fungus; but, wishing to make a study of the water, such cultures 

 were undertaken. As the fungus developed abundantly on the liver fed to the fish, 

 if it remained a few days in the water, this was first used for culture experiments, but 

 bacteria were developed in such numbers on the meat that it was found useless, and flies 

 — the only insects to be had — were resorted to with fairly good results. It was desired 

 to test the water immediately before its entrance to the tanks, in order to learn if the 

 germs were then present; to test it in the different tanks, and in various parts of the 

 same tank, to ascertain if the germs were present or absent, or relatively more or less 

 abundant in the different situations ; and, lastly, to determine if different fungous forms 

 existed in the water taken from these various places. An examination of water taken 

 directly from the lake and of the hygeia water used for drinking purposes on the 

 Exposition grounds, was also made. 



The method pursued was as follows : A small bottle of the water to be tested was 

 taken and a fly or two dropped in it and left for twenty-four hours — a sufficient time 

 for the infection of the fly if fungous germs were present — when the water was replaced 

 by that known to be pure. Twenty-four hours later, if the culture was successful, a 

 slight growth of the fungus could be seen radiating from the insect, and one or two 

 days thereafter the zoosporangia began to form. After the expiration of a week, 



*Ledermuller, Mikroskopische Ergotzungen, 1760. 



