KEY TO RECOGNITION OF THE SARCINA. 153 



pearance of the bouillon cultures is of little value in differ- 

 entiating species, as it seems that most varieties finally 

 produce a more or less viscous or friable sediment in the 

 clear bouillon, and that in the same variety the character 

 of this sediment varies. The precipitate either forms upon 

 the bottom or on the walls and bottom, without the bouillon 

 becoming cloudy ; or the precipitation is preceded by a 

 longer or shorter diffuse cloudiness of the bouillon. The 

 bouillon takes on in some varieties (Sarc. alba), but not 

 always, a characteristic gummy, viscous quality. 



The following presentation is dependent not only upon 

 our own studies, but upon the critical elaboration of the 

 material, which Dr. Stubenrath cultivated during about 

 two years under our direction, and upon which he has re- 

 ported in a monograph, ' ' Das Genus Sarcina, ' ' Miinchen, 

 1897. The literature is there extensively presented. 



Space does not allow us to enter more into particulars 

 concerning the uncritically described and very numerous 

 varieties of Henrici 1 and Gruber 2 . Stubenrath (I. c.) has 

 referred to the fact that those contributions, in a work 

 which does not at all consider the variation of bacteria, 

 have loaded us with many names, but that our knowledge 

 is scarcely advanced thereby. 



Key to Recognition of the Sarcinae. 



I. Without Pigment Production upon Agar and Gelatin. 

 (a) Potato growth delicate, brownish-yellow from the first. Gela- 

 tin and agar growth, delicate, finely notched and wrinkled. Young 

 cultures motile, old cultures often with spores. Sarc. pulmonum 

 Virchow, page 155. 



(6) Potato growth always remains white or grayish-white, 

 (a) Gelatin plate magnified sixty times; very finely granular; 



limited liquefaction. No formation of large regular bales of 



packets. Sarc. alba Zimmermann, page 160. 

 (j3) Gelatin plate magnified sixty times; medium-sized granules; 



liquefaction more rapid; formation of beautiful regular bales 



of packets. Sarc. canescens Stubenrath, page 159. 



II. Upon Agar and Gelatin Grayish- yellow, Greenish-yel- 

 low to Chrome- yellow. 



(a) Gelatin plate magnified sixty times ; very finely granular ; 



1 Henrici, " Beitrag zur Bakterienflora des Kases" (A. K. Bd. 

 1,1). 



2 Gruber, "Die Arten der Gattung Sarcina " (A. K. Bd I, 241). 



