New YorK AGRICULTURAL EXPERIMENT STATION. 155 
mediately transferred to each of three broth tubes to test 
sterility. In none of these, neither in any of several similarly 
tested later, did growth develop, showing beyond question that 
this softening of the tissues was due solely to the bacterial 
products which diffused through the layer of agar from the 
surface colony above. Upon more carefully examining the 
turnip Slice it was found that there was a slight softening of 
the surface over the entire area covered by the agar, b-b, of 
the diagram Fig. 2. The area immediately underlying the 
colony was softened much more deeply however viz., about 
1-1144mm. The deepest softening occurred in a circle about 
2mm. wide underlying the margin of the colony, lying between 
d and din the accompanying diagram, (Fig 2). Micro- 
Scopic examination showed exactly similar conditions to those 
which accompany bacterial invasion, viz., isolation of the cells 
as a result of the solution of the middle lamellae, with the 
residual walls swollen and taking a blue stain upon treatment 
with chlor-zinc-iodide, and the protoplasmic contents showing 
granulation and plasmolysis. 
Several other dishes examined after twenty-four to thirty- 
six hours show results practically like the above except that 
in most of them the softening was to a uniform depth of 
1-2 mm. immediately’ underlying the colonies with a gradual 
decrease in this depth, as shown in the accompanying diagram 
which is drawn to exact scale as to size of colony and degree 
of softening at the end of twenty-four hours. 
In connection with the above work we also conducted simi- 
lar transplantations of colony-bearing layers of agar to the 
surface of sterile gelatin plates. [Examination in such cases 
at the end of three days revealed liquefaction of the gelatin 
underlying the colony, but for an area equalling about twice 
the diameter of the colony above, and to a depth of one to two 
millimeters. Transfers from this liquefied gelatin to broth 
tubes proved its sterility and showed that the action here, as 
in the case of the vegetable tissues, was due to the diffusion 
of the bacterial products from the colony through the inter- 
vening agar, 
