138 IOWA ACADEMY OF SCIENCES. 



and rats. Old cultures, however, soon loose their virulence. 

 A culture nine months old failed to cause any lesions in mice, 

 not even the local formation of pus. 



St. pyogenes, Ogston var. citreua Passet. — This species has 

 not been found spontaneously in any of the cases of pus 

 studied, though it has been cultivated in the laboratory. 

 It has been included with the pyogenic cocci because of its 

 occurrence in pus. Passet found the organism in the pus of 

 an acute abscess and Sternberg* says: "As to its pathogenic 

 properties, we have no definite information. It is included 

 among the pyogenic bacteria because of occasional presence in 

 the pus of acute abscesses, although it has heretofore only been 

 found in association with other micro-organisms." Mice have 

 been inoculated here at Ames but in no case did fatal sep- 

 ticaemia follow. We have, however, had no trouble in obtain- 

 ing pus at the point of inoculation under the root of the tail. 

 From this pus, pure cultures of the organisms were obtained. 



St. pyogenes Ogston var., flavescens Trev. — Obtained from the 

 fistula of a horse by Dr. S. Whitbeck in bacteriological labora- 

 tory, Iowa Agricultural college. This organism does not 

 differ from the foregoing in size; in color, however, it is much 

 paler, being an ochre yellow. It produces fatal septicaemia in 

 mice when fresh cultures were used, but in this case pure 

 cultures were not obtained. 



Streptococcus cinncibareus , Fltigge. — Obtained at first from 

 butter, but probably came either from the air or water. Color 

 in different media is quite constant, except in blood serum, 

 where its color is much paler. It grows quite characteristic 

 on the surface of bouillon, forming spherical masses paler than 

 in agar or potato. A nearly related species was isolated by 

 Dr. W. B. Niles from the heart of a diseased steer affected with 

 corn- stalk disease. It differs from the cinnabarcus in the 

 change of color. It is dark lemon-yellow at first, and then 

 changes to a brick-red. This species will be described in 

 another connection. 



Sarcina lutea SchrOter.— This well known organism occurs 

 chiefly in the air. Gelatin and agar plates exposed to the air 

 invariably show this organism. It comes up somewhat more 

 tardily than the non-chromogenic species. They appear as 

 small, yellow, spherical colonies. The canary-yellow growth 

 liquefies gelatin quite slowly. The same organism has been 



(Manual of Bacteriology p. 27J. 



