38 Proceedings of Royal Society of Edinburgh. [sess. 
and Indians , were produced which grew on gelatine without any 
signs of liquefaction. The condition was not, however, a very 
permanent one in cholera, as after a certain time a slow liquefaction 
of the gelatine began to show itself. 
In the case of all the organisms, the longer they were subjected 
to the influence of carbolic acid the more fixed was the new condition. 
On the other hand, the strongest solutions in which the organism 
could he got to grow were not those best suited for the production 
of more permanent species. No doubt, the enzymes were lost more 
quickly by the use of the higher concentrations, but on recultivation 
on other media they almost immediately returned. It would ap- 
pear that the carbolic acid, by acting de vital isingly on the proto- 
plasm as a whole, restricted the exercise of that lower function, which 
by replacing its enzyme action, prevented the tendency to relapse 
reasserting itself, when cultivated again under normal conditions. 
At any rate, it was the use of medium concentrations over more 
prolonged periods which were found most effective, and indications 
were not wanting that a previous growth of the microbe in the more 
dilute solutions would have produced evenbetter results. The enzyme 
which acted on the gelatine, and that which occasioned the rennet- 
like separation of the casein in milk, were not affected alike in these 
experiments. In all three organisms the power of coagulating the 
milk appeared to be lost before the power of liquefying the gelatine. 
If this were so, one might consider the rennet-like ferment as being 
a later evolved function, and so more easily lost when subjected to 
degrading influences. For, as the precipitation of the casein is only 
a splitting, preliminary to the peptonisation which is to follow, such 
an enzyme would be of no use to the organism unless the peptonising 
power were also present. The absolute proof that it is first lost, is 
however wanting, as another factor must here be taken into con- 
sideration. These organisms become more sensitive to acid reaction 
in proportion to the loss of their enzyme action, as is evidenced by 
their less vigorous growth on potato. Now, as they all produce 
acid from the sugar in milk, their further enzyme production may be 
inhibited by the acid they themselves have formed before such fer- 
ment is present in sufficient quantity to cause the precipitation of 
the casein. 
It may be mentioned here that Prodigiosus and Indicus, which 
