The jury looked up, interested.

"I believe," continued Lawrence, "that there have been cases
where the cumulative effect of a drug, administered for some
time, has ended by causing death. Also, is it not possible that
she may have taken an overdose of her medicine by accident?"

"This is the first we have heard of the deceased taking
strychnine at the time of her death. We are much obliged to you,
Mr. Cavendish."

Dr. Wilkins was recalled and ridiculed the idea.

"What Mr. Cavendish suggests is quite impossible. Any doctor
would tell you the same. Strychnine is, in a certain sense, a
cumulative poison, but it would be quite impossible for it to
result in sudden death in this way. There would have to be a
long period of chronic symptoms which would at once have
attracted my attention. The whole thing is absurd."

"And the second suggestion? That Mrs. Inglethorp may have
inadvertently taken an overdose?"

"Three, or even four doses, would not have resulted in death.
Mrs. Inglethorp always had an extra large amount of medicine made
up at a time, as she dealt with Coot's, the Cash Chemists in
Tadminster. She would have had to take very nearly the whole
bottle to account for the amount of strychnine found at the
post-mortem."