FOREST, FISH AND GAME COMMISSIONER. 219 



tinguished by their color from the white muscle. These spots quickly 

 develop into sores which break through the overlying flesh. Previously, 

 however, the skin gradually bulges out so that swellings from the size of a 

 pea to the size of a nut exist. The inside of this sore contains a bloody, 

 watery mass of broken-down muscle tissues, ulcers and numberless bacteria. 

 After the perforation of the sores flat ulcers of different sizes appear, most 

 of them not larger than a five-cent piece. The sores extend deep, and from 

 the open sores fistulas lead into the muscles from which at times a foul 

 colored, bloody mucus flows. In most of the affected fish the bottom of the 

 sore is covered over only with a small quantity of pus, which is continually 

 washed awav through the water by the movements of the fish. 



In the circle of the ulcers not yet broken out appear distended ecchy- 

 moses which are seen here and there on the skin of the body and the gills. 

 When the ulcers appear the fish, in from eight to fourteen days, become 

 very sluggish in their movements. They separate themselves from their 

 comrades, locate on the edges of the pond and are easily caught by hand. 

 Frequently they show, at various places on the body, epithelium spots — 

 gray spots — on which fungus growths very soon appear proceeding from 

 Saprolegnia or Achlya. 



According to the studies of Semmerich and Weibel as to the causes of 

 the ulcer disease it originates with infection by Bacteria salmonicida, which 

 as it shows itself from the intestine outward, as far as possible penetrates 

 even the skin of the body and attacks every organ. It is seen very easily 

 in the blood and also in the kidney, liver, and muscles. 



These statements of Semmerich and Weibel have been confirmed by 

 the author in many experiments in different places. At the beginning of 

 the disease the author has repeatedly discovered that it is most likely to 

 occur where there is putrefaction on the bottom of the pond and in the 

 water. The ulcer disease may appear in ponds which have swampy bot- 

 toms, or in which the water trickles over swampy earth. It may, therefore, 

 be found in ponds which are connected with a sewer pipe or drainage from 

 manure heaps. It appears most readily, however, when in the course of 

 artificial feeding remains of food in excess foul the bottom. 



The course of the disease is usually short. Death generally occurs 

 from two to three weeks after infection. There is, however, a milder 



