Final answer:
Mercy describes Ruth's illness as a gradual wasting away of the person with occasional cataleptic episodes.
Step-by-step explanation:
Mercy describes Ruth's illness as a "gradual wasting away of the person" with "frequent although transient affections of a partially cataleptical character." This means that Ruth's illness causes her to gradually become weaker and thinner, and she experiences occasional episodes of a condition called catalepsy, which is characterized by muscle stiffness and immobility.