e-histories as
are debatable or still undetermined.

Of these methods, some are new, others are not; but all are reliable,
only such having been included as are capable of giving satisfactory
results even in the hands of beginners. In fact, the bulk of the matter
is simply an elaboration of the typewritten notes distributed to some of
my laboratory classes in practical and applied bacteriology;
consequently an attempt has been made to present the elements of
bacteriological technique in their logical sequence.

I make no apology for the space devoted to illustrations, nearly all of
which have been prepared especially for this volume; for a picture, if
good, possesses a higher educational value and conveys a more accurate
impression than a page of print; and even sketches of apparatus serve a
distinct purpose in suggesting to the student those alterations and
modifications which may be rendered necessary or advisable by the
character of his laboratory equipment.

The excellent and appropriate terminology introduced by Chester in his
recent work on "Determinative Bacteriology" I have adopted in its
entirety, for I consider it only needs to be used to convince one of its
extreme utility, whilst its inclusion in an elementary manual is
calculated to induce in the student habits of accurate observation and
concise description.

With the exception of Section XVII--"Outlines for the Study of
Pathogenic Bacteria"--introduced with the idea of completing the volume
from the point of view of the medical and dental student, the work has
been arranged to allow of its use as a laboratory guide by the technical
student generally, whether of brewing, dairying, or agriculture.

So alive am I to its many inperfections that it appears almost
superfluous to state that the book is in no sense intended as a rival to
the many and excellent manuals of bacteriology at present in use, but
aims only at supplementing the usually scanty details of technique, and
at instructing the student how to fit up and adapt apparatus for his
daily work, and how to carry out thoroughly and systematically the
various bacterioscopical analyses that are daily demanded of the
bacteriologist by the hygienist.

Finally, it is with much pleasure that I acknowledge the valuable
assistance received from my late assistant, Mr. J. B. Gall, A. I. C., in
the preparation of the section dealing with the chemical products of
bacterial life, and which has been based upon