NATURE 



361 



THURSDAY, FEBRUARY 18, 1SS6 



PRACTICAL BACTERIOLOGY 

 An Introduction to Practical Bacteriology, based upon the 

 Methods of Koch. By Edgar M. Crookshank, M.B. 

 (Lond.), F.R.M.S., Demonstrator of Physiology, King's 

 College, London. (London : H. K. Lewis, 1886.) 



THIS excellent work is based upon notes made in 

 difterent Continental, laboratories, and is intended 

 to be a laboratory hand-book as well as a text-book of 

 bacteriology, including as it does "a systematic sketch of 

 the genera and species of micro-organisms, as well as the 

 methods employed in the investigation of their life- 

 histories." The science is intimately connected with 

 the etiology of the infectious and contagious diseases, 

 and by enlarging knowledge as to the origin, causes, 

 and spread of these diseases, has greatly aided, 

 and may be expected in the future greatly more to 

 aid, in the acquisition of knowledge as to the mea- 

 sures necessary to be adopted for their prevention ; 

 nevertheless it has received attention in this country from 

 but a few earnest inquirers, the great mass of information 

 now at our disposal having been accumulated in Germany- 

 This fact is apparent at once on glancing through the 

 pages of this book ; for every English work, six German 

 at least are referred to as having been consulted by the 

 author. Apart also from its association with medical 

 pathology, the subject is of the greatest interest to the 

 naturalist, be he botanist or zoologist. It is only necessary 

 to refer to the work of Pasteur in this connection for a 

 proof of the vast amount of benefit to commerce and 

 science which may still be anticipated to arise from a 

 fuller knowledge of the life-histories of those organisms 

 which are associated with so many diseases of plants, 

 animals, and men. The importance of a study, not 

 merely of the pathogenic or disease-producing, but of all 

 the different species of Bacteria and Fungi is fully grasped 

 by the author in the following paragraph : " It is impos- 

 sible, by localising one's knowledge to pathogenic species 

 to thoroughly understand the life-history of these par- 

 ticular forms, or to be able to grasp and appreciate the 

 various arguments and questions that arise in comparing 

 their life-history with the progress of disease." 



The postulates formulated by Koch for establishing the 

 exact relationship, and ascertaining beyond question 

 whether a micro-organism associated with disease is 

 actually the cause of that disease, are quoted by the 

 author in the introductory chapter, and bearing as they 

 do so intimately on the controversies which have raged 

 over the relations of micro-organisms to disease, especially 

 of Koch's comma-bacilli to Asiatic cholera, may be given 

 here. They are as follows : — (a) The micro-organism 

 must be found in the blood, lymph, or diseased tissues of 

 man, or animal, suffering from, or dead of, the disease. 

 {b) The micro-organisms must be isolated from the blood, 

 lymph, or tissues, and cultivated in suitable media, i.e. 

 outside the animal body. These pure cultivations must 

 be carried on through successive generations of the 

 organism. (<) A pure cultivation thus obtained must, 

 when introduced into the body of a healthy animal, pro- 

 duce the disease in question, {d) Lastly, in the inocu- 

 VoL. XXXIII.— No. 851 



lated animal the same micro-organism must again be 

 found. 



The first part of the work is devoted to a description 

 of the "apparatus, material, and reagents employed in a 

 bacteriological laboratory"; to the methods employed for 

 the " microscopical examination of Bacteria in liquids, in 

 cultivations on solid media, and in tissues " ; to the " pre- 

 paration and staining of tissue sections " ; to the " pre- 

 paration of nutrient media and methods of cultivation " ; 

 to the subject of " experiments upon living animals " ; 

 and to the method of " examination of animals experi- 

 mented upon, and the methods of isolating micro- 

 organisms from the living and dead subject." 



The multiplicity and complexity of the apparatus, 

 materials, and reagents required for this work, and the 

 great care and nicety in manipulation necessary for its 

 proper execution, may well dismay the scientific inquirer 

 who wishes to make a practical study of the subject. 

 The expense alone of fitting up a laboratory on the lines 

 indicated by our author, must form a great obstacle in 

 the path of the would-be student. The license to experi- 

 ment upon animals which would be necessary for a 

 thoroughly systematic investigation is, as is now well 

 known, most difficult to obtain. And yet there is no 

 laboratory in this country at which such investigations 

 could be undertaken by any one at a moderate expense. 

 Surely London is rich enough, and earnest enough in the 

 cause of sanitary progress, to found an establishment on 

 the model of the Hygienic Laboratory at Berlin. There 

 is fortunately no lack of men, thoroughly capable of 

 undertaking its supervision, and its popularity and useful- 

 nesy would not be a matter of doubt to those who are 

 acquainted with the work of the Biological Laboratory at 

 the Health Exhibition of 1884. 



Part II. is "systematic and descriptive, with special 

 microscopical methods," and commences with the history 

 of our knowledge of Bacteria, the difficult question of 

 classification being also here dealt with. In 1872 Cohn 

 published his first classification. He considered the 

 Bacteria to be a distinct group belonging to the Algje, 

 but from the absence of chlorophyll allied to the Fungi, 

 and divided them into four tribes according to their shape, 

 as globules, short rods, long rods, and spirals, these four 

 tribes including six genera. In 1875 Cohn, in answer to 

 Billroth, who disputed the division into species, consider- 

 ing that all the forms described by Cohn were but deve- 

 lopmental forms of one organism, Coccobacteria septica, 

 propounded a second classification, in which he still 

 maintained that distinct genera and species existed. The 

 genera Cohn considered to be distinguished by definite 

 differences in shape, which were adhered to throughout 

 life, while some special feature, as a difference in size or 

 physiological action, or some minute difference in form, 

 determined the various species. " Researches," writes 

 our author, " by competent observers have quite recently 

 clearly demonstrated that several micro-organisms in 

 their Jife-cycle exhibit successively the shapes charac- 

 teristic of the orders of Cohn. This had as early as 1873 

 been observed by Lister in a Bacterium in milk. Lister 

 detected forms of Cocci, Bacteria, Bacilli, and Streptothrix 

 genetically connected." Recent observers also have ob- 

 tained similar results, so that the very foundation of 

 Cohn's classification has been shaken, and "we are left 



