INTRODUCTORY. 3 



b. The micro-organisms must be isolated from 

 the blood, lymph, or tissues, and cultivated in suit- 

 able media, i.e., outside the animal body. These 

 pure cultivations must be carried on through succes- 

 sive generations of the organism. 



c. 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 inoculated animal the same 

 micro-organism must again be found. 



These points would naturally suggest a sequence 

 in the various processes which must be adopted in 

 a practical study of micro-organisms associated with 

 disease. Inasmuch, however, as these processes 

 embrace those which are employed in the isolation, 

 cultivation, etc., of non- pathogenic species, we shall, 

 in studying the bacteria as a whole, adopt the order 

 suggested. After an introduction to the apparatus 

 commonly employed in a bacteriological laboratory, 

 we shall describe the methods of examining liquids, 

 tissues, etc., and the means of recognising micro- 

 organisms. Then will follow the methods of 

 isolating these micro-organisms from such liquids, 

 tissues, etc., and of carrying on pure cultivations 

 in nutrient media. Lastly, we shall refer briefly 

 to experimental researches on the living animal, 

 and the means of isolating micro-organisms from the 

 liquids and tissues of the body after death. 



In Part II. will be found chapters upon the 

 General Biology of bacteria, and in Part III. a 



