300 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



luted by waste matters from any manufacturing establishment; tlie 

 appearance of this epidemic, therefore, cannot be attributed to this 

 cause. Moreover, symptoms of disease have never been noticed among 

 the fish inhabiting this river. 



Max von dem Borne proceeded to experiments, which seem to show 

 that the cause of the disease is found, if not in the water, at least in the 

 mud of the river. He said : 



" I caused to be sent me by a leading fisherman of Soldin (a locality 

 further np the river than Berneuchen, and not yet contaminated) some 

 perfectly healthy crawfish, which I placed in a cemented trough at ray 

 establishment. This trough was traversed by a strong current of water 

 coming from the Mietzel, and the bottom was covered with a layer of 

 mud taken from the same river, but no diseased or dead crawfish was 

 put in this trough. Nevertheless, at the end of nine days all the healthy 

 crawfish which I had placed there began to show signs of disease, 

 and in a day or two afterwards all were dead. I always noticed the 

 following symptoms : The crawfish contracts on one side ; it continually 

 rubs its head and eyes with its walking claws ; the whitish color of the 

 lower part of the abdomen becomes red ; and the animal lies on its back 

 and dies. It is worth saying, however, that the crawfish which I placed 

 under observation on the 18th and 26th of last November have remained 

 perfectly healthy up to the present, and they are even occupied iu 

 spawning." 



At the request of Max von dem Borne, von Liustow*, physician of 

 the staff-office at Hameln, has given special attention to this disease 

 among crawfish, and the examination of a great number of these crus- 

 taceans which he has made leads him to admit that he is certainly in 

 the presence of a parasitic disease. Dr. von Linstow has also stated 

 that the disease propagates itself in ascending watercourses. As soon 

 as they feel the disease the crawfish become restless. Generally they 

 leave the water, wander around on the banks, and on the way usually 

 lose some claws and often their pinchers, and finally they lie on their 

 backs and die. 



Like Max von dem Borne, Dr. von Linstow believes that the water 

 contains the cause of the mischief, and that it serves as a vehicle for it. 

 He has seen, in fact, that if healthy crawfish coming from localities as 

 yet uncontaminated are placed in streams where tlie epidemic rages, 

 these crustaceans are quickly attacked by the disease and destroyed in 

 a little while. 



Dr. von Liustow says : " The researches made with a view of discov- 

 ering the cause of the evil have given rise to different opinions. Ac- 

 cording to Professor Harz, of Munich, the disease might be caused by 

 the trematode, now for a long time known under the name of Distoma 

 cirrigerum, which might invade the muscles of crawfish iu great num- 

 bers. My attention was then immediately directed to this parasite, but 



" Mittheilungen dea Herrn Dr. von Linstow in Hameln iiher dig sogenannte Krebspest, 



