SYSTEMATIC AND DESCRIPTIVE. 2 I I 



in nutrient agar-agar in a test-tube, they form a 

 colourless growth along the track of the needle, 

 and a bright canary-yellow layer upon the surface, 

 v/here they have access to the air (Plate XIII., 

 Fig. i, Plate VIII., Fig. i). In plate-cultivations the 

 colonies are round, slightly granular in appearance, 

 and yellow. Cultivated in a test-tube containing 

 nutrient gelatine, they grow rapidly ; the gelatine 

 becoming liquid, the yellow growth forms a wad 

 about the middle of the tube (Plate V., Fig. 2), or, 

 liquefying the whole of the gelatine, subsides to 

 the bottom of the test-tube. Cultivated on sterilised 

 potatoes they form a yellow layer (Plate X., Fig i). 

 In drop-cultures in bouillon the subdivision into 

 tetrads within tetrads and formation of groups of 

 8, 1 6, and 24 can be studied (Plate I., Fig. 7). In- 

 oculation of mice produces negative results. The 

 cocci are occasionally present in the air. 



Sarcina aurantiaca. Cocci singly, in pairs, 

 in tetrads, and in packets. They form small 

 orange-yellow colonies on plate-cultivations, and 

 in test-tubes slowly liquefy the gelatine along the 

 whole needle track, forming on the surface an 

 orange-yellow growth. On potatoes they slowly 

 develop the same pigment. 



Sarcina ventriculi, Goodsir.* Cocci reach- 

 ing 4 p. in diam., united in groups of four, or 

 multiples of four, producing cubes or packets with 

 rounded-orf corners. Contents of the cells are 



* Goodsir, Edinburgh Med. and Surg. Journal. 1842. 



