It turned out that this sucrose was not necessary for the homogenate and once they set up the experiment without sucrose they were able to see more effective results.
They hypothesised that some viral inhibitory factor was present in the tissues infected with virus and attempted to isolate and characterize this factor from tissue homogenates.
The key to the success of this experiment was the use a homogenate of liver cells rather than intact liver cells, as they had been doing in their previous experiments.