This is an OCR edition without illustrations or index. It may have numerous typos or missing text. However, purchasers can download a free scanned copy of the original rare book from GeneralBooksClub.com. You can also preview excerpts from the book there. Purchasers are also entitled to a free trial membership in the General Books Club where they can select from more than a million books without charge. Original Published by: The University of Chicago Press in 1905 in 235 pages; Subjects: Bacteriology; Juvenile Nonfiction / Science & Nature / General; Science / General; Science / Life Sciences / Bacteriology; Science / History; Science / Life Sciences / Biology / Microbiology; Science / Philosophy & Social Aspects;