IQO RELATIONSHIPS OF THE COCCACE^ 



certain of their native powers. The occurrence of these 

 forms is rare. Of our one hundred and eighty cultures 

 of orange chromogens, one hundred and thirty-five were 

 from the normal or diseased body, only six from earth, 

 six from water, and thirty-three from air. The infre- 

 quency with which orange cocci have been described 

 from sources other than the body makes it clear that 

 there is no important saprophytic source for organisms 

 of this type. 



One exception must be noted to the general rule, dis- 

 cussed in Chapter IV, — that the chromogenic cocci of the 

 body are orange pigment formers, and the saprophytic cocci 

 of the earth and water are yellow. It is well recognized that 

 staphylococci producing a lemon yellow pigment {Staphy- 

 lococcus pyogenes citreus, Passet) are found in appreciable 

 numbers on the normal skin and occasionally penetrate 

 the tissues in disease. Otto (1903) has shown that these 

 yellow forms produce hemolysins and leucocidins and 

 react to agglutinins, just as the pathogenic aurococci and 

 albococci do. Only a careful quantitative study of the 

 acid production, gelatin liquefaction, and chromogenic 

 power in a considerable series of these forms will show 

 whether they are aurococci which have suffered a change 

 in pigment production, or micrococci which have acquired 

 pathogenic powers. In our investigation we have exam- 

 ined thirteen cultures of pathogenic yellow pigment 

 formers, and this small number showed low acid produc- 

 tion, a generally negative reaction to the Gram stain, and a 



