For the defence it was urged by Montagu Williams that it was admitted by the scientific witnesses for the prosecution that they had no other proof of the identity of aconitine than these physiological tests upon mice; that their conclusions were a leap in the dark; and that mice had so delicate a constitution that even an injection of pure water would kill them. How then could it fairly be argued that because these little animals had been killed by an injection of a substance extracted from the body, that substance must be aconitine? Apart from that, bodies of the nature of alkaloids were formed in the body by decomposition, and the effects upon the mice attributed to aconitine might very well have been caused by one of these alkaloids.
It was further pointed out that there had been no opportunity of giving the boy a pill without the knowledge of the schoolmaster, and that the prisoner could not have charged the capsule with aconitine without having been observed.
The evidence put forward by the prosecution carried conviction to the jury, and the prisoner was found guilty and sentenced to death.
With reference to the more important points raised by the defence it may be mentioned that no known ptomaine (i.e., alkaloid formed by decomposition in the body after death) produces the same physiological effects as aconitine, and that the conclusions of Dr. Stevenson and Dr. Dupré were based upon the results of comparative tests, which showed that as little as 1⁄2000 grain of aconitine could be recognised in this way.
The probable solution of the mystery of how the prisoner managed to give the poison to the boy is suggested in the reminiscences of Lord Brampton, who, as Sir Henry Hawkins, was the presiding judge at the trial. He points out that Lamson was far too clever a man to attempt such a clumsy plan as to charge the capsule with aconitine, and thus draw suspicion upon himself. The much more plausible theory is that the capsules had nothing whatever to do with the poisoning but that Lamson had previously put the aconitine into a raisin in the cake, and had taken care that his young brother-in-law should get the slice containing that raisin, while he and the schoolmaster had eaten other portions of the otherwise harmless cake.
After sentence of death had been passed, Lamson stood with his arms folded and in a loud voice proclaimed his innocence before God. Before his execution, however, it is stated that he confessed that he had not only poisoned Percy John, but also his other brother-in-law Herbert.
CHAPTER XV
THE MAYBRICK CASE