ways. I suspect, however, that a purely mental
effort will be sufficient to disperse these nauseous shadow-things.
Probably you will not be troubled again to-night, but whenever the
phenomena return, take off your coat to them! You require no better
companion than the one you had:--Mark Twain! Treat your visitors as
one might imagine he would have treated them; as a very poor joke! But
whenever it begins again, ring me up. Don't hesitate, whatever the
hour. I shall be at the hospital all day, but from seven onward I
shall be here and shall make a point of remaining. Give me a call when
you return, now, and if there is no earlier occasion, another in the
morning. Then rely upon my active co-operation throughout the
following night."

"Active, sir?"

"I said active, Rob. The next repetition of these manifestations shall
be the last. Good-night. Remember, you have only to lift the receiver
to know that you are not alone in your fight."

Robert Cairn took a second cigar, lighted it, finished his whisky, and
squared his shoulders.

"Good-night, sir," he said. "I shan't run away a third time!"

When the door had closed upon his exit, Dr. Cairn resumed his restless
pacing up and down the library. He had given Roman counsel, for he had
sent his son out to face, alone, a real and dreadful danger. Only thus
could he hope to save him, but nevertheless it had been hard. The next
fight would be a fight to the finish, for Robert had said, "I shan't
run away a third time;" and he was a man of his word.

As Dr. Cairn had declared, the manifestations belonged to one of two
varieties. According to the most ancient science in the world, the
science by which the Egyptians, and perhaps even earlier peoples,
ordered their lives, we share this, our plane of existence, with
certain other creatures, often called Elementals. Mercifully, these
fearsome entities are invisible to our normal sight, just as the finer
tones of music are inaudible to our normal powers of hearing.

Victims of delirium tremens, opium smokers, and other debauchees,
artificially open that finer, latent power of vision; and the horrors
which surround them are not imaginary but are Elementals attracted to
the victim by his peculiar excesses.

The crawling things, then, which reeked abominably might be Elementals
(so Dr. Cairn reasoned) superimposed upon Robert Cairn's consciousness
by a directing, malignant intelligence. On the other hand they might
be mere glamour