232 REPORT OF THE COMMISSIONER OF FISH AND FISHERIES. 



Ill the 3 German streams Trepliu^ believes 3 series of cases to be dis- 



tinjiuisliable: (1) Mostly small fisli(ui) to 100 grams), still well nomislicd, 

 with only iiuliN'idual, or without recognizable, indurated patelies, and 

 which present m the abdominal region, at most, 1 hard tumor. (2) 

 Somewhat larger fish (up to 200 grams), which almost always show in 

 several x>h^ces on their sides hard, somewhat swollen, patches; also 

 tumors similar to those on the smaller fishes, mostly on the abdominal 

 region. These fishes already begin to emaciate. (3) Fishes of and 

 above the preceding weights, showing on the sides, belly, or back large 

 ulcers, mostly lying immediately under the skin. A i)art of the same 

 is already broken up; borders foul and red; interior containing a yellow 

 pus. The fishes have emaciated greatly, and die. 



Season, Itailliet thinks, appears to have no inlluence, fish being seen 

 dead in nudwinter as well as in June, July, and August. 



Pollution of streams Kailliet considers a minor factor, saying: 



The diversion into the Meuse ot" manufactory refuse is often hhanied for the existence 

 of this condition of affairs, hut the investigations of M. Ladague tend to incriminate 

 rather the erection of dams at certain points on the river, these structures diminish- 

 ing the rapidity of current, in the midst of which the barbel ordinarily lives. 



Treplin ' believed that the young barbels receive the germ from 

 refuse deposits of industrial establishments (breweries, malt houses, 

 tanneries, distilleries, etc.) on the headwater of the Saar andMosel; 

 and, further, that these germs enter by the alimentary canal, passing 

 thence into the rest of the body, and first make their exit therefrom 

 {via the ulcers) in the second or third year. Herr Hanzo,^ on the 

 contrary, considers the cloth and paper mills as chiefly responsible, as 

 these establishments handle old rags which are, he says, saturated with 

 infective material. 



Of the views of Treplin and Hanzo, Ludwig considers that of Treplin 

 to have the greater degree of probability. Both, however, he remarks, 

 consist only of opinions and probabilities, and further leave out of sight 

 other sources of contamination. While no sufficient evidence exists for 

 holding pollution of water by different indnstrial establishments respon- 

 sible for barbel myxosporidiosis, an indirect connection between such 

 water pollution and the disease is by no means to be entirely rejected. 

 It is very easily possible that such pollution may favor myxos]>oridian 

 increase and development, and esi)ccially that it may, by injuriously 

 affecting the general life conditions, diminish the normal resistive 

 power of the fish, thus rendering infection more easy. This view ex- 

 plains the fact {fide the fishermen) that the barbels at Bonn recover, 

 while they die in the Saar and Mosel, in which latter streams pollution 

 must, on account of the smaller volume of water, affect the fish more 

 injuriously. 



M. Brauu •' places less stress upon fouling of the water, as once 



' In liUdwig, Jahresber. rhein. Fisch.-Vereins, IJonn, 1888, p. 34. 



'^ In Ludwig, loc. cit., ])p. 31, 35. 



^Review of Ludwig iu Centralbl. f. Bakt. n. Patasitenkde, 1889, v, p. 420. 



