“Chief among them,” he proceeded, “are those from nature’s own laboratory.  There are some sixty species of serpents, for example, with deadly venom.  Among these, as you doubtless have all heard, none has brought greater terror to mankind than the cobra-di-capello, the Naja tripudians of India.  It is unnecessary for me to describe the cobra or to say anything about the countless thousands who have yielded up their lives to it.  I have here a small quantity of the venom”—­he indicated it in a glass beaker.  “It was obtained in New York, and I have tested it on guinea-pigs.  It has lost none of its potency.”

I fancied that there was a feeling of relief when Kennedy by his actions indicated that he was not going to repeat the test.

“This venom,” he continued, “dries in the air into a substance like small scales, soluble in water but not in alcohol.  It has only a slightly acrid taste and odour, and, strange to say, is inoffensive on the tongue or mucous surfaces, even in considerable quantities.  All we know about it is that in an open wound it is deadly swift in action.”

It was difficult to sit unmoved at the thought that before us, in only a few grains of the stuff, was enough to kill us all if it were introduced into a scratch of our skin.

“Until recently chemistry was powerless to solve the enigma, the microscope to detect its presence, or pathology to explain the reason for its deadly effect.  And even now, about all we know is that autopsical research reveals absolutely nothing but the general disorganisation of the blood corpuscles.  In fact, such poisoning is best known by the peculiar symptoms—­the vertigo, weak legs, and falling jaw.  The victim is unable to speak or swallow, but is fully sensible.  He has nausea, paralysis, an accelerated pulse at first followed rapidly by a weakening, with breath slow and laboured.  The pupils are contracted, but react to the last, and he dies in convulsions like asphyxia.  It is both a blood and a nerve poison.”

As Kennedy proceeded, Mrs. Maitland never took her large eyes from his face.

Kennedy now drew from a large envelope in which he protected it, the typewritten note which had been found on Maitland.  He said nothing about the “suicide” as he quietly began a new line of accumulating evidence.

“There is an increasing use of the typewriting machine for the production of spurious papers,” he began, rattling the note significantly.  “It is partly due to the great increase in the use of the typewriter generally, but more than all is it due to the erroneous idea that fraudulent typewriting cannot be detected.  The fact is that the typewriter is perhaps a worse means of concealing identity than is disguised handwriting.  It does not afford the effective protection to the criminal that is supposed.  On the contrary, the typewriting of a fraudulent document may be the direct means by which it can be traced to its source.  First we have to determine what kind of machine a certain piece of writing was done with, then what particular machine.”