DESCRIPTION OF PLATE XIX. 

 Pure-cultivations of Actinomyces. 



These tubes were selected from a great number of cultivations 

 in which there were different appearances. In some instances the 

 growths had a faint tinge of pink. 



FIG. 1. Pure-cultivation on the surface of potato, showing a luxuriant 

 sulphur-yellow growth entirely composed of entangled masses of fila- 

 ments. After three months' growth. 



FIG. 2. Pure-culture from the same series, on glycerine-agar. In this case 

 the culture remained perfectly white. The jelly was coloured reddish- 

 brown. After fifteen months' growth. 



FIG. 3. Pure-culture on glycerine-agar in which the growth was dark- 

 brown, in parts black, and the jelly stained dark-brown. After nearly 

 two years' growth. 



