132 
FRANK 8. BILLINGS. 
are attached to it, the individual colonies will develop as in the 
older gelatine, especially at first; but they soon grow larger, and 
finally coalesce, forming a continuous development along the line 
of puncture. Along the sides of the same, the small, individual 
colonies are indicated hy its delicate serrated appearance. I have 
seen this organism, when inoculated into old gelatine, retain the 
isolated colonial appearance for a period of two months without 
any attempt at coalescence between the colonies. 
They never cause the gelatine to become fluid. 
They are as anaerobic and aerobic; that is, develop equally 
well with or without contact with the air. They develop as a 
sharply circumscribed coating of a grayish-white color upon the 
surface of freshly made gelatine, but not too profusely. 
They lose their virulent activities quite rapidly in, or upon, 
artificial cultivations, but not so rapidly when access to the air is 
shut off. Thus far I have only been able to test their virulence 
upon a very limited number of rabbits, mice and rats, and have 
tested them by some forty experiments upon hogs, on account of 
paucity of funds. 
They will kill rabbits, when a small quantity (two drops) of a 
fresh and virulent culture is used, in from three to five days, and 
mice in from twenty-four to thirty-six hours. Rats succumb to 
larger quantities (ten drops) in from thirty to forty-eight hours, 
or more. Their action upon hogs varies greatly according to the 
amount injected and the locality chosen for such interference; 
but above all, the germs vary very much in virulence in different 
outbreaks and in different localities, even when pigs or hogs are 
inoculated directly with a piece of freshly removed spleen rubbed 
up in sterilized boullion. How long cultivations will retain their 
virulence I am unable to say at present, but I have been success¬ 
ful with a proportionately large quantity of the tenth generation 
of the first cultivation, on the 28tli of October last, the material 
having been obtained the July previous. 
They develop fairly well on potatoes, the colonies assuming a 
rich coffee color; that is, of good coffee when good cream has 
been added to it. On beets, turnips and carrots I have not ob¬ 
served any particularities worthy of mention. 
