706 



SCIENCE. 



[N. S. Vol. XVI. No. 409. 



above title appeared in Science for August 

 22, had been discussed long ago by L. Natan- 

 son in Wiedemann's Annalen; and lie adds: 

 " This same explanation [referring to mine], 

 only in a much more complete form, was given 

 by JSTatanson more than thirteen years ago." 



I am glad to learn of the very interesting 

 article which treats of the same subject and 

 which was not knovsm to me. 



But the treatment and even the object of 

 L. Natanson's article and of my communica- 

 tion are, contrary to Mr. Wood's opinion, 

 widely different. Natanson treats the subject 

 in an elaborate quantitative manner, leaving 

 practically out of consideration the qualitative 

 side of the phenomenon (i. e., the question 

 how it happens that the slow and quick mole- 

 cules become separated), while I direct my 

 attention only to its qualitative aspect, having 

 attempted to form a simple idea of the 

 mechanism of the phenomenon. 



From a statement in his note I see that Mr. 

 Wood misread the abstract; this made it 

 difficult for him to understand its contents. 

 Peter Fireman. 



Washington, D. C, 

 October 16, 1902. 



SHORTER ARTICLES. 

 BACTERIUM TRUTT^, A NEW SPECIES OF BAC- 

 TERIUM PATHOGENIC TO TROUT. 



This organism was obtained from the blood 

 of diseased brook trout and stands in specific 

 causal relation to the disease. The following 

 characterization will be followed by a more 

 extended description. 



It is a pleomorphic form which appears in 

 the blood and local lesions of its host as longer 

 or shorter rods, with occasional spherical 

 forms. The rods grow out infrequently into 

 filaments of 6 fi, but average much less, and 

 may be scarcely 0.5 ,a in length. The width 

 is 0.5 to 1.0 /J. On nutrient agar-agar it 

 assumes the form of a spherical or subspherical 

 coccus, with occasional rods, the cocci 0.5 to 

 1.0 ;j. in diameter. Microscopically the field 

 gives the impression of cocci, but the rods are 

 not infrequent and reach a maximmn length 

 of 1.5 //. In liquid media rods greatly pre- 

 dominate, often arranged in pairs, of a length 



from that of the diameter of a coccus up to a 

 maximum of 2.35 ,u, and 0.48 to 0.83 fi wide. 

 Many of the single rods, when stained, show 

 a slight constriction indicating their separa- 

 tion into cocci, while many give no sign what- 

 ever of such a structure. Agar plates made 

 from the blood contain apparently pure cul- 

 tures of the organism as colonies chiefly of 

 cocci, which become chiefly rods when trans- 

 ferred to bouillon, or when inoculated into 

 trout. In the latter case they reproduce the 

 disease, appear in the blood and lesions as 

 rods recoverable upon agar as cocci. This 

 pleomorphism in different media and the 

 variety of form in the same culture are not 

 reduced by repeated plating. 



The organism is non-motile, does not form 

 spores, and a capsule has not been demon- 

 strated. It stains readily by aqueous solutions 

 of the ordinary aniline dyes, and faintly by 

 Gram's method, but its reaction with this 

 stain is not of much value. It grows aerobic- 

 ally on ordinary nutrient media, luxuriantly 

 on agar of a reaction* neutral or -|-0.5 to 

 phenolphthalein, and will not grow or but 

 very slightly at -|-1.5; at — 0.5 growth is 

 inhibited and at — 1.0 to — 1.5 scarcely occurs. 

 On agar slants growth is moderately abundant, 

 of a grayish-white color, with age grayish- 

 brown. On usually the third day a production 

 of a soluble pigment becomes evident, which 

 diffuses itself in the medium and does not 

 reside in the growth itself. It is a brown 

 shade and deepens gradually, becoming very 

 dark brown after two or three weeks, and the 

 growth itself taking on a brown tinge. This 

 pigment is produced in agar, bouillon, Dun- 

 ham's pepton solution, and coagulated blood 

 serum but not in gelatine or upon potato. It 

 is produced in alkaline, neutral and acid 

 media and is inhibited by extremes of reaction 

 as the growth itself of the organism is in- 

 hibited. It is produced at the room tempera- 

 ture. Higher temperatures inhibit the color 

 faster than they do the growth. 



Agar plate surface colonies are round, 

 slightly convex, outline well defined, micro- 

 scopically granular, after two days grumose 



* Report Committee of Bacteriologists, Journ. 

 Amer. Pub. Health Assoc, January, 1898. 



