REPORT OF COMMISSIONER OF FISH AND FISHERIES. CXLV 



directions under the skiu and muscles. Changes in the blood are i^resent, 

 most marked in the colored corpuscles, which, instead of having tho 

 regular elliptical outline, present irregular and bizarre sbapes, consti 

 tuting poikilocytosis. The blood is found to be teeming with bacteria; 

 chiefly streptococci, which appear to explain the condition of the cor 

 puscles; the tissues and viscera also contain large numbers of bacteria. 



Microscopic examination of the tissues, with the usual culture experi' 

 ments, indicates that the disease is a septictemia, caused by infection 

 by a streptococcus. The disorganization of the blood leads to mal 

 nutrition of the tissues, followed by softening and rupture of the vessel 

 walls and the escape of blood into the tissues. The extravasation 

 becomes purulent, with the results stated. 



The disease originated in one pond and spread thence to two othei' 

 ponds into which the first pond discharged. The fact that other poud;j 

 supplied by the same (spring) water escaped the epidemic shows a local 

 source of infection, and acquits the water of any responsibility. Thi;5 

 was further demonstrated by a careful examination of the water. By 

 drawing off the water in the first i^ond it was found that planks which 

 formed the sides of the pond were rotten below the level of the gravel 

 bottom of the pond, and that the cracks and softened spots therei)i 

 were filled with organic debris. From cultures made from the rotting 

 wood, and the vegetable and animal matter thereon, streptococci and 

 staphylococci developed in great numbers, those most prevalent beiuj? 

 Streptococcus pyogenes^ Staphylococcus pyogenes aureus^ and Stophylococcns 

 pyogenes alhus. The removal of the woodwork of the ponds and the 

 substitution of cement or stone linings have been recommended. 



Cod-tagging experiment. — The tagging of adult cod at the Woods Hole 

 station, referred to in the last division report, was continued during 

 the winter of 1898-99. The number of cod tagged was 593, which, with 

 those previously liberated, make 1,155 tagged fish released in the 

 adjacent waters. The number of tags thus far recovered from the firi;t 

 lot is 31; by June 30, 1899, the number returned from the second sea- 

 son's plant was 23. The recaptured fish furnish information regarding 

 the movements, rate of travel, growth, etc., of the cod. The tagging 

 will be carried on during another season. 



Aquatic fauna in vicinity of liatching-stations. — The hatcheries of the 

 Commission are annually visited by large numbers of persons, some of 

 whom are merely sight-seers, while others are in search of information. 

 The stations, in their respectiv^e communities, are regarded as centers 

 of information on all matters pertaining to fishes and aquatic animals 

 in general, in addition to purely fish-cultural subjects. In order to 

 increase the usefulness of hatcheries in this respect arrangements are 

 being made to i^rovide for each station a series of labeled specimens 

 representing all the species of fishes and other water animals found in 

 the vicinity. As a preliminary step, this division supplied a collecting 

 seine and preserving media to the various superintendents, some of 

 whom have already obtained very complete collections. 



F C 99— X 



