"And from certain knowledge I have gained through various experiences,"
he continued calmly, "I can diagnose your case as I said before to be
one of psychical invasion."

"And the nature of this--er--invasion?" stammered the bewildered writer
of humorous tales.

"There is no reason why I should not say at once that I do not yet quite
know," replied Dr. Silence. "I may first have to make one or two
experiments--"

"On me?" gasped Pender, catching his breath.

"Not exactly," the doctor said, with a grave smile, "but with your
assistance, perhaps. I shall want to test the conditions of the
house--to ascertain, impossible, the character of the forces, of this
strange personality that has been haunting you--"

"At present you have no idea exactly who--what--why--" asked the
other in a wild flurry of interest, dread and amazement.

"I have a very good idea, but no proof rather," returned the doctor.
"The effects of the drug in altering the scale of time and space, and
merging the senses have nothing primarily to do with the invasion. They
come to any one who is fool enough to take an experimental dose. It is
the other features of your case that are unusual. You see, you are now
in touch with certain violent emotions, desires, purposes, still active
in this house, that were produced in the past by some powerful and evil
personality that lived here. How long ago, or why they still persist so
forcibly, I cannot positively say. But I should judge that they are