The following abstract gives some account of putrefaction, and may be of use in conjunction with the account of the bacteriology of the bate which has been given. Since it was written Dr. G. Abt (see Bibliography 51) has also given a very full description of putrefactive processes as affecting leather manufacture. The subject is still occupying the attention of a large number of bacteriologists, and we may expect more light to be thrown on the whole question during the next few years. ABSTRACT OF PAPER ON RECENT ADVANCES IN THE BACTERIOLOGY OF PUTREFACTION. Read before the Nottingham section of the Society of Chemical Industry, January 24, 1906.[91] [91] Reprinted from the Journal of the Society of Chemical Industry, February 15, 1906, No. 3, vol. xxv. The numbers in brackets refer to the Bibliography, Chapter XI. To those who have to do with the manufacture of leather, the changes which take place in the skin from the time it leaves the animal are of the utmost interest. The most important of these changes is the natural process of decomposition known as putrefaction. Putrefaction may be defined as the decomposition of nitrogenous organic matter by living organisms, accompanied by the evolution of malodorous gases. The study of it may be divided into two parts--(1) the biological, (2) the chemical. The first concerns the organisms which break down the proteid molecule either directly or by means of enzymes; the second that of the different products of the action of these organisms. It is extremely difficult to separate these two studies. Dr. Sims Woodhead (59) gives a concise account of the earliest researches on the organisms causing putrefaction by Leeuwenhoek (1692), Plenciz of Vienna, Müller of Copenhagen (1786), Needham (1749), Spallanzani (1769), Schwann (1837), Schroeder and Van Dusch (1854), Tyndall (1870), Lister (1878). These names show that the history of putrefaction proceeds parallel with the evolution of the microscope and the development of the comparatively recent science of bacteriology. I propose to-night briefly to carry it up to the present day.