Answer:
the author's purpose is to persuade readers that sugar production created a system that relied on slavery but also paved the way for revolution
Doctors warned people to stay away from the medical tent where patients were being treated in order to avoid contagion. This means to avoid the spread or transfer of diseases or infection. Contagion means the communication of illnesses from one person to another, most especially when in close contact.
There is an envelope marked with the instructions that it is not to be opened until the death or disappearance of Dr. Jekyll. This implies that Dr. Lanyon knew something secret, but was unwilling to reveal it at first. He waited until there was no more "hope" of Dr. Jekyll staying normal.
The dicipline between the 2 schools
