foundation of vital phenomena. For the physiologist this
perfection of the compound microscope had the same significance
that the, discovery of America had for the fifteenth-century
geographers--it promised a veritable world of utterly novel
revelations. Nor was the fulfilment of that promise long delayed.

Indeed, so numerous and so important were the discoveries now
made in the realm of minute anatomy that the rise of histology to
the rank of an independent science may be said to date from this
period. Hitherto, ever since the discovery of magnifying-glasses,
there had been here and there a man, such as Leuwenhoek or
Malpighi, gifted with exceptional vision, and perhaps unusually
happy in his conjectures, who made important contributions to the
knowledge of the minute structure of organic tissues; but now of
a sudden it became possible for the veriest tyro to confirm or
refute the laborious observations of these pioneers, while the
skilled observer could step easily beyond the barriers of vision
that hitherto were quite impassable. And so, naturally enough,
the physiologists of the fourth decade of the nineteenth century
rushed as eagerly into the new realm of the microscope as, for
example, their successors of to-day are exploring the realm of
the X-ray.

Lister himself, who had become an eager interrogator of the
instrument he had perfected, made many important discoveries, the
most notable being his final settlement of the long-mooted
question as to the true form of the red corpuscles of the human
blood. In reality, as everybody knows nowadays, these are
biconcave disks, but owing to their peculiar figure it is easily
possible to misinterpret the appearances they present when seen