Craig pulled down from the shelf above him one of his well-thumbed
standard works on toxicology. He turned the pages and read:

"Pure aconite is probably the most actively poisonous substance
with which we are acquainted. It does not produce any decidedly
characteristic post-mortem appearances, and, in fact, there is no
reliable chemical test to prove its presence. The chances of its
detection in the body after death are very slight."

Dr. Leslie looked up. "Then there is no test, none?" he asked.

"There is one that is brand new," replied Kennedy slowly. "It is
the new starch-grain test just discovered by Professor Reichert,
of the University of Pennsylvania. The peculiarities of the starch
grains of various plants are quite as great as those of the blood
crystals, which, you will recall, Walter, we used once.

"The starch grains of the poison have remained in the wound. I
have recovered them from the dead man's blood and have studied
them microscopically. They can be definitely recognized. This is
plainly a case of aconite poisoning--probably suggested to the
Oriental mind by the poison arrows of the Ainus of Northern
Japan."

Dr. Leslie and I both looked through the microscope, comparing the
starch grains which Kennedy had discovered with those of scores of
micro-photographs which lay scattered over the table.

"There are several treatments for aconite poisoning," ruminated