L   i
. Infectious Abortion of Cows. E 267 » i  
_ sixty degrees for one hour, thus destroying the life of the -  
ion organism, and then examined. l  
S;p0ruZcti0n.eNone 'observed. °  
Plain Ag0wi.——Our experience indicates that this bacillus  
grows nearly as well on plain. agar when standardized neutral W  
(faintly pink) to-phenolphthalein as it does on serum-agar, ‘ _  
[ in Then, too, we have been more successful in getting less spread  
ont of foreign germs on plain agar and thus a larger number of  
Ml isolated colonies of the Abortusbacillus than where serum- ‘  
agar is used. In fact, we have discarded serum in isolating  
me cultures from the placentas of aborting cows, although in _  
» some instances no doubt serum is indispensible in obtaining a  
ish- culture direct from the tissues. Two per cent. agar is especial- _  
ly preferred to a less amount in isolating the germ from the ' I  
uterine exudate of an aborting cow when contaminated with .  
mlf other bacteria, as it gives a firmer medium on which to make  
the streak dilutions than where a less per cent. agar is used.  
We use infusions of fresh beef instead of beef extract in mak- · t_ 
lout _ ing our agars and bouillons, as we believe it better because of l » it 
. the muscle sugars which it contains. l  
fo,. 4 Petri Dish C2llt2m·e.—The surface (colonies grown in a  
T closed jar with Bacillus subtilis are transparent to transmitted  
sam light and have a bluish or greenish color according to angle ,;§g·;iti7 _
of reflected light. The color, however, of young colonies to  
by ` reflected light is decidedly bluish. To direct light the young  
`OM colonies (three days old) look like minute dew drops and are  
;o1’s homogeneous with the exception that now and then a colony  
ium may be seen with a few granules in the center (see plate 2).  
lade When incubated for a day or two longer there are usually U  
llumerous colonies having granules in their centers (see plate  
g at 5) and colonies resulting from six days incubation or longer,  
1.€c_ though quite transparent to transmitted light, assume Some  
ld a c_ amber color. To reflected light they take on a greenish blue   ..g_.i.’ l
lism tinge and the center of the colony may have a whitish appear-   s 4
mes alice. As such a colony is magnified 20 to 30 diameters it can p ·,>~¤‘g;;j
amo ` be Dlélinly seen that its center has assumed somewhatiof a  
d at C031`S€ly granular consistency, the granules becoming smaller   so
l0W3rd the circumference of the colony. The outer portion    
l.%