ETIOLOGICAL MOMENT OF AMERICAN SWINE PLAGUE. 131 
three times its mature length, the two colored ends still more dis¬ 
tant from one another and connected by a fine filament. The 
next step is the ovoid coccus which has colored diffusely; it be¬ 
comes still more oval; from it now develops the mature organ¬ 
ism ; the oval object increases, so slightly, in length, and a deli¬ 
cate, non-refracting, non-coloring or white line separates it into 
two parts and increases very rapidly in quantity, separating the 
two refracting ends which bound it on either side. 
The mature organism is again before your eyes! 
This phenomenon can best be seen in the hanging drop cul¬ 
ture to which some coloring material has been added. 
When the artificial cultivations have been held at a tempera¬ 
ture under 25° C., these organisms assume a sort of dwarfed de¬ 
velopment; their bodies become shorter, or if of normal length 
they are thinner; the ends and non-colored middle piece being no 
longer so easily differentiated; the white substance is scarcely 
perceptible, and the coccoid ends smaller. In one culture one 
can see a perfect swarm of coccus-like objects of all dimensions, 
but none so large as in freshly sowed cultures. Such cultivations 
must be re-inoculated upon fresh material very frequently. They 
retain their vitality best upon blood serum or in boullion. They 
do fairly well upon sterilized agar agar, peptonized meat infusion 
developing in a dirty white mass. They develop rather poorly in 
gelatine, yet cultivations in this medium have more or less bio¬ 
diagnostic value. In quite old gelatine, which has become some¬ 
what hard from evaporation, but not hard enough to crack upon 
puncturing it, they develop slowly and in small colonies along 
the line of puncture, which gives to the same the appearance of a 
delicate thread with small knots at intervals along its course ; the 
knots corresponding to individual colonies. Cultivations in such 
old gelatine do not have the tendency to spread over the super¬ 
ficial surface that they do upon freshly made gelatine, because of 
the hardness of the surface and the want of sufficient moisture. 
In freshly made meat infusion peptonized gelatine, the first 
seen bio-pnenomena are somewhat dependent upon the size of the 
wire and number of germs upon it, when the medium is inocu¬ 
lated. If the wire is delicate and the number of germs small that 
