FOOT-AND-MOUTH DISEASE. 
489 
to have discovered the germ peculiar to this disease. His method 
of investigation was as follows : He inoculated alkaline peptones, 
broth, and solid agar-agar, peptone hroth mixture, solid nutritive 
gelatine mixture, and milk, with lymph which was obtained from 
the vesicles of diseased sheep. He discovered after a few days, a 
thin film, limited in extent, npon the surface of the solid media at 
and near the point of puncture. The film gradually spread, pre¬ 
senting a very characteristic appearance, namely a collection of 
closely packed minute granules or droplets. These enlarge slowly 
and gradually, and become whitish and translucent in character. 
If the point of a needle or platinum wire be moistened with the 
lymph and pushed into the solid medium, the line of puncture 
becomes marked as a linear aggregation of minute granules or 
droplets after several days or weeks. There is also, in addition 
to this, on the surface of the culture media the film of granules 
already alluded to, which starts from the point of inoculation. 
This micrococcus grows very slowly, the first indication of its 
growth in solid nutritive gelatine mixture, at a temperature of 
18° to 22° C., becoming visible under a lens at the end of from 
five to eight days, or still later. The growth thus developed ap¬ 
pears in the form of a small cluster of transparent granules. In 
agar-agar mixture, kept at 35° to 38° C., the growth is sooner 
visible, although, after six or seven months, “in all media and 
under all conditions the growth remains of limited extent.” 
When milk is inoculated with the micrococcus, and kept at a tem¬ 
perature varying between 35° and 38° C., the growth is found to 
progress very slowly. The condition and natural appearance of 
the milk are not changed. No curdling occurs, but the reaction 
becomes acid. The micrococcus forms in artificial media dumb¬ 
bells (diplococcus) and beautiful chains (streptococcus). These 
vary in length according to the number of micrococci com¬ 
posing them, “ the short chains being a linear series of four, 
six or eight micrococci, the longer ones of more than eight 
up to thirty and more micrococci.” The longer chains are always 
curved, and even convoluted. 
The above mentioned characteristic appearance of the growth 
jg owing to the presence of smaller or larger masses of chain mat- 
