CULTIVATION OF MIC. MELITENSIS. 453 



It stains fairly readily with the ordinary basic aniline stains, but 

 loses the stain in Gram's method. It is generally said to be 

 a non-motile organism. Gor- 

 don, however, is of a contrary , v - 

 opinion, and has recently dem- 

 onstrated that it possesses from ** ^ 

 one to four flagella, which, how- , \ " . ' * % *\ , ' '* * 

 ever, are difficult to stain. In . * \ % / % % * .. * 

 the spleen of a patient dead * t *j* * '' ^ 

 of the disease it occurs irregu- f * ^ ' ' * ". x .. 

 larly scattered through the -. .** % 

 congested pulp. It may also *, * . , 



be found in small numbers "V *, : - 



". 



post mortem in the capillaries 



Of Various Organs, but exami- FIG. i S4 . Micrococcus melitensis, from 



nation of the blood during a two days' culture on agar at 37 C. 

 . . Stained with fuchsin. x 1000. 



life gives negative results. It 



can, however, be obtained by puncture of the spleen during 



life. 



Cultivation. This can usually readily be effected by making 

 stroke-cultures on agar tubes from the spleen pulp and incu- 

 bating at 37 C. The colonies, which are usually not visible 

 before the third day, appear as small round discs, slightly raised 

 and of somewhat transparent appearance. The maximum size 

 2-3 mm. in diameter is reached about the ninth day; at 

 this period by reflected light they appear pearly white, while by 

 transmitted light they have a yellowish tint in the centre, bluish 

 white at the periphery. A stroke-culture shows a layer of 

 growth of similar appearance with somewhat serrated margins. 

 Old cultures assume a buff tint. The optimum temperature is 

 37 C., but growth still occurs down to about 20 C. On gelatin 

 at summer temperature growth is extremely slow after two or 

 three weeks, in a puncture culture, there is a delicate line of 

 growth along the needle track and a small flat expansion of 

 growth on the surface. There is no liquefaction of the medium. 



In bouillon there occurs a general turbidity with flocculent 

 deposit at the bottom ; on the surface there is no formation of 

 a pellicle. On potatoes no visible growth takes place even at 

 the body temperature, though the organism multiplies to a certain 

 extent. 



