PREFACE 
9 
serology as possible, including the problems of carriers, 
Schick’s test, Plotz’s work on the etiology of typhus, the 
work of Cole and his coworkers on pneumonia, the prom¬ 
ising work of Bull on the serum therapy of the gas bacil¬ 
lus infection, the complement-fixation test for tuberculo¬ 
sis, etc. 
My sincere thanks are due to my many friends for 
various favors conferred upon me in connection with 
the preparation of this work, and it affords me great 
pleasure to express my gratitude to Mr. Bichard Fluent 
for the excellent photographs and to Mr. Daniel E. 
Quilter for his valuable aid in the preparation of the chap¬ 
ters on the “Bacteria in the Soil, Air, Water, and Milk.” 
Mr. S. Coopersmith was very kind in arranging the 
different apparatus for the preparation of the photo¬ 
graphs. 
My sincere thanks are due to my very good friend, 
Dr. James E. Hallisy, for his kind help in the prepara¬ 
tion of the index as well as the reading of the final proof. 
Arthur A. Eisenberg. 
Cleveland, Ohio. 
