the victim of a sudden and complete loss of memory.

This dislocation of memory is a variety of aphasia known as
amnesia, and when the memory is recurrently lost and restored, we
have alternating personality. The Society for Psychical Research
and many eminent psychologists, among them the late William James,
Dr. Weir Mitchell, Dr. Hodgson of Boston, and Dr. A. E. Osborn of
San Francisco, have reported many cases of alternating
personality.

Studious efforts are being made to understand and to explain the
strange type of mental phenomena exhibited in these cases, but as
yet no one has given a clear and comprehensive explanation of
them. Such cases are by no means always connected with
disappearances, and exhaustive studies have been made of types of
alternating personality that have from first to last been
carefully watched by scientists of the first rank.

The variety known as the ambulatory type, where the patient
suddenly loses all knowledge of his own identity and of the past
and takes himself off, leaving no trace or clue, is the variety
which the present case of Miss Blackwell seems to suggest.

There followed a number of most interesting cases and an elaborate
argument by the writer to show that Betty Blackwell was a victim
of this psychological aberration, that she was, in other words, "a
vanisher."

I laid down the paper with a questioning look at Kennedy.