104 SPECIAL BACTERIOLOGY 



Biological Characters. The actinomyces is a typical streptothrix 

 possessing all the characteristics peculiar to that species. It is anaerobic 

 and facultatively aerobic. Some authorities state that the growth is 

 best under anaerobic conditions when first obtained from the animal 

 body, while others consider it grows best aerobic. 



On Gelatine Plates, in six days a very limited greyish-yellow growth 

 develops, sometimes on the surface and sometimes in the depth of the 

 medium. 



In Gelatine Stab Cultures. At the commencement a du)l yellowish- 

 white, elevated, shining compact growth develops on the surface of the 

 medium, sinking later from slight liquefaction of the gelatine ; along the 

 track of the needle small yellowish-white knots develop at first, bristly 

 outgrowths appearing later. 



On Plain and Glycerine Agar opaque nodules about the size of a pin- 

 head, which remain isolated for weeks or months, develop, the peripheries 

 being formed of a fine delicate network. Large white nodules about 

 the size of a lentil (rosette forms) sometimes also develop (see Photo- 

 graph, Fig. 31). 



On the oblique surface of Blood Serum the individual granules exhibit a 

 yellowish brick or red-rose colour, covered with whitish downy filaments 

 or threads. 



In Bouillon the medium is not clouded, but round masses are formed 

 in the bottom of the tube, which are separated with difficulty by 

 shaking. 



In Milk a granular growth takes place, followed by gradual peptonising. 



On Potatoes the growth presents a yellowish-red colour, covered with 

 a downy mass of threads. 



In Eggs. It grows well in pigeon and hen's eggs, either raw or when 

 cooked for three or four minutes (prepare the egg and inoculate accord- 

 ing to Giinther's method see Technique, page 52). The prepared egg is 

 placed in the incubator with the inoculated end uppermost, and exa- 

 mined in from nine to twenty-eight days ; if no putrefaction has taken 

 place or decolorization, the growth appears in raw eggs both in the 

 white and in the yelk, and cloudy masses of slime resembling nasal 

 mucus develop in the albumen. In cooked eggs opaque white spots of ' 

 the size of pin-heads develop between the yelk and white, and finally a 

 mass is formed in the track of inoculation and on the surface of the 

 coagulated albumen. 



Microscopical Examination of Cultures. The growths on agar 

 media consist mostly of short rods mostly straight, but often comma 

 shaped, or sometimes further bent. The dimensions of the rods vary ; 

 they may appear plump and thick, very slender and short, or in long 

 thick rods, and sometimes club or olive-shaped at the ends (see Photo- 



