PREFACE TO THE SECOND EDITION.

IN preparing this second edition of u Pathogenic Bac-
teria '' I have endeavored to bring the work up to date
in all departments of the subject by introducing brief
mention of all recent work accomplished in bacteriology.
In order to aid the student whose particular interest
might make him desire to refer to the original papers,
I have thought well to depart from the plan of the orig-
inal work and give the references in the form of foot-
notes.

Without departing too much from the primary descrip-
tive purpose of the book, I have made it a special point
to add considerably to the amount of technique it con-
tains, and so make it fulfill the double purpose of a sys-
tematic work upon bacteria and a laboratory guide.

New chapters have been added dealing with the bac-
teriology of Whooping-cough, Mumps, Yellow Fever,
Hog-cholera, and Swine-plague ; describing the Bacillus
aerogenes capsulatus and the Proteus vulgaris; and
describing the Methods of Determining the Value of
Antiseptics and Germicides, and of Determining the
Thermal Death-point.

To a number of friendly readers whose suggestions
have been helpful in improving the work, I desire to
extend my sincere thanks.

JOSEPH