m by him for years after their escape
from the South. He noted from time to time certain curious changes that
took place in his physical nature, and recorded his observations with
scientific precision in a book kept for the purpose, for the renewal of
life had entailed results of an extraordinary character, as the reader
may have already anticipated. At length he wrote 'My hypothesis is
verified, it has become a theory. My theory is proved, it is a
physiological law. _Climatic influences, acting upon man, bring about
physical changes exceedingly slowly, because they are resisted by an
inveterate habit of assimilation which pertains to the blood._'

That day Shirley was free. His rescuer had finished his experiment.

Alice Wentworth had never believed that her lover was dead. She had
heard all with a troubled heart, but while his distant kinsmen, who were
heirs-at-law, put on the deepest mourning and grew impatient of the
law's delay, she simply said, "I will wait until there is some proof
before I give him up! Proof! proof! Shall I be quicker than the law to
give up every hope?" And in her heart she said, "He is not dead." Even
when years had passed and the war was over, and her agent had searched
everywhere and found no trace of him, she did not cease to hope that he
would yet appear. So, when at length a letter came, it was welcome and
expected. Not surprise but joy made her start and tremble as the old
familiar superscription met her eyes.

Such a letter!--filled with the spirit of his love, breathing in every
word the tender, passionate devotion of an earlier day, and yet so sad.
Tears dropped down through her smiles of joy and blurred the lines she
read at first, but smiles and tears alike ceased as she read on. He had
written many, many times, but he knew she had not got his letters. He
had been a prisoner--not only prisoner of war, but afterward prisoner to
a man whose will was iron. It could hardly be explained. This man had
not only saved his life, but he had also rescued him from the horrors of
a Southern prison--would God he had let him die!--and they had been
living together in a ranch in a far off Mexican valley.

Then the letter went on:

"In my heart I am unchanged; my love for you is ever the same; yet I am
no longer the Robert Shirley whom you knew. That has come upon me which
will separate me from you for ever: I cannot ask you now to be my wife.
You are free. It is through no fault of mine. It is