Bacteriologic Diagnosis 



When the sloping surface of inoculated agar-agar is ex- 

 amined by transmitted light, the appearance of the colonies 

 is somewhat different. At the end of nine or ten days, if 

 kept at 37 C., some of the colonies have a diameter of 2 to 3 

 mm. They are round in form, have an even contour, are 

 slightly raised above the surface of the agar-agar, and are 

 smooth and shining in appearance. On examining the 

 colonies by transmitted light, the center of each is seen to 

 be yellowish, while the periphery is bluish-white in color. 

 The same colonies by reflected light appear milky white in 

 color. Colonies on the surface of the agar-agar are found 

 to be no larger than hemp-seed after a couple of months 

 of cultivation. 



When kept at 25 C., no colonies become visible to the 



* - 



Fig. 169. Micrococcus melitensis. 



naked eye before the seventh day; at 37 C., before the 

 third or fourth day. 



The growth in gelatin takes place at room temperature 

 with great slowness, first appearing in about a month, 

 and no liquefaction of the medium occurs. 



No growth takes place on boiled potato. 



Plate cultures are not adapted to the study of the organ- 

 ism because of its extreme slowness of growth. 



Bacteriologic Diagnosis. The specific agglutinative 

 effect of the serum can be made use of for the purpose 



