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 . *" - . 

 opinion, and has recently dem- <t, • ,• • ^ ^ _ 

 onstrated that it possesses from : ,* ^ , . ' 

 one to four flagella, which, how- •^'' ' ' \ \ » • .' '*' 

 ever, are difficult to stain. In . ' * .^ _• " tf ^ • . • 

 the spleen of a patient dead '. ji.**" '• -» • ; 

 of the disease it occurs irregu- . . * '* ' . • ■ 

 larly scattered through the , .'•' « •. " , 

 congested pulp. It may also * *» " , • 

 be found in small numbers , ** . " 

 /'ost mortem in the capillaries 



of various organs, but exami- fig. 154. - 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 gclatiti 

 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. 



