PREFACE. 5 



cations that can be found of almost every known procedure. 

 The methods that are described are those which have stood 

 the severe test of the practical instruction indicated above. 

 Many of the methods, as well as some of the apparatus 

 described, have originated in this laboratory. Illustrations 

 of the various bacteria and of their cultural characteristics 

 have been expressly omitted, inasmuch as the student is 

 eixpected to sketch from observation the form of each 

 organism and its. peculiarities of growth in the colony, and 

 in tube culture. Blank pages are provided for this purpose 

 and for such additional notes as may be desirable. 



More space has not been given to the consideration of 

 the individual pathogenic bacteria, and of questions of 

 immunity, for the reason that these and allied subjects are 

 treated of in a general course of lectures which is wholly 

 independent from the laboratory work. These lectures on 

 general bacteriology are given daily and extend throughout 

 a semester. Prom the standpoint of a teacher it is desir- 

 able that the two courses be kept distinct, and for that 

 reason the treatment of the general subject should be pub- 

 lished separately, if at all. An exception is made in the 

 case of the first five chapters, which deal with the general 

 properties of bacteria, and which, as such, are necessary 

 for reading and reference in connection with the laboratory 

 work. 



The last two chapters are devoted to special methods 

 which will be of value to advanced students. Several of 

 the characteristic ingenious methods of the Pasteur school 

 are given at length. Here, as elsewhere in the book, the 



