-tight in
every house. The water in these is periodically examined by officers
from the waterworks, who ascertain that it has contracted no impurity
either in the course of its passage through hundreds of miles of
piping or in the cisterns themselves. The Martialists consider that to
this careful purification of their water they owe in great measure
their exemption from the epidemic diseases which were formerly not
infrequent. They maintain that all such diseases are caused by organic
self-multiplying germs, and laugh to scorn the doctrine of spontaneous
generation, either of disease, or of even such low organic life as can
propagate it. I suggested that the atmosphere itself must, if their
theory were true, convey the microscopic seeds of disease even more
freely and universally than the water.

"Doubtless," replied our guide, "it would scatter them more widely;
but it does not enable them to penetrate and germinate in the body
half so easily as when conveyed by water. You must be aware that the
lining of the upper air-passages arrests most of the impurities
contained in the inhaled air before it comes into contact with the
blood in the lungs themselves. Moreover, the extirpation of one
disease after another, the careful isolation of all infectious cases,
and the destruction of every article that could preserve or convey the
poisonous germs, has in the course of ages enabled us utterly to
destroy them."

This did not seem to me consistent with the confession that disorders
of one kind or another still not infrequently decimate their
highly-bred domestic animals, however the human race itself may have
been secured against contagion. I did not, however, feel competent to
argue the question with one who had evidently studied physiology much
more deeply than myself; and had mastered the records of an experience
infinitely longer, guided by knowledge far more accurate, than is
possessed by the most accomplished of Terrestrial physiologists.

The examination of these works of course occupied us for a long time,
and obliged us to traverse several miles of ground. More than once I
had suggested to Eveena that we should leave our work unfinished, and
on every opportunity had insisted that she should rest. I had been too
keenly interested in the latter part of the explanation given me, to
detect the fatigue she anxiously sought to conceal; but when we left
the works, I was more annoyed than surprised to find that the walk
do