84 



SOLID CULTIVA TION MEDIA. 



One of the best known species cultivated in gelatine is the Bacillus 

 anthracis (Figs. 37 and 43), which grows downwards in the track of the 

 inoculating wire in small round nodules of the size of grains of sand, 

 and of a dull pale yellow colour, and gradually liquefies the contents 



j.i 1. 



Fig. 39. Fig. 40. 



Fig. 39. — Cultivation of pink yeast in nutrient jelly, showing the 

 brighter pink colour of the surface growth. 



Fig. 40. — Cultivation of micrococci found in vaccine lymph. 



a. Yellow growth on the surface. 



b. Growth of small rounded white masses along the tracks of the 



needle. 



c. Cleft in the gelatine, from increased surface tension produced 



by evaporation. 



of the test-tube from above downwards, till in the course of six to 

 eight weeks the whole mass has become liquid. At the bottom of the 



