232 EEPORT OF THE COMMISSIONER OF FISH AND FISHERIES. 



In the 3 German streams Treplin^ believes 3 series of cases to be dis- 

 tingnishable : (1) Mostly small fish (up to 100 grams), still well nonrished, 

 with only i'.idividual, or without recognizable, indurated patches, aud 

 w^hich present in the abdominal region, at most, 1 hard tumor. (U) 

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

 several places 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, Eailliet thinks, appears to have no iufiueuce, fish being seen 

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



Pollution of streams Eailliet considers a minor factor, saying: 



The (liversiou iuto tlie Mense of mauufactory refuse is often blamed for the existence 

 of this condition of affairs, but tlie investigations of M. Ladague tend to incrimiuate 

 rather th<i erection of (hims at certain points on the river, these structrires diminish- 

 ing the rapidity of current, in tlie 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 and Mosel; 

 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 Hauzo,^ 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 j)robabilities, and further leave out of sight 

 other sources of contamination. While no sufficient evidence exists for 

 holding i)ollution of water by dift'erent industrial establishments resiDon- 

 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 myxosporidiau 

 increase and development, and especially that it may, by injuriously 

 aifecting 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, afiect the fish more 

 injuriously. 



M. Braun^ ])laces less stress upon fouling of the water, as once 



1 In Ludwig, Jahresber. rhein. Fisch.-Vereins, Bonn, 1888, p. 34. 



2 In Ludwig, loc. cit., pp. 34, 35. 



^Review of Ludwig in Centralbl. f. Bakt. u. Parasitenkde, 1889, V, p. 420. 



