VI PREFACE. 



organisms, yet when it was required of them to outline the procedure 

 by which they would differentiate members of the typhoid-colon groups 

 when encountered in a plate made from feces, the problem appeared 

 to them impossible. They possessed the information, but did not 

 know how to apply it. 



In practical work, organisms can only be separated culturally by the 

 use of Keys and for this reason Keys are given at the beginning of each 

 division of bacteria. These enable one to quickly place the organism 

 isolated in its respective group. Only methods of differentiation which 

 are applicable in a physician's private laboratory are given. Practical 

 methods for making the final identification by agglutination or other 

 immunity tests are described. Technic for immunizing animals to 

 furnish such sera is given in detail. 



The giving of the cultural characteristics in a systematic tabulated 

 Key gives space in the notes for presenting the salient points in the 

 pathological and epidemiological aspects of each organism. 



I have endeavored to give a scientific yet practical classification of the 

 important pathogenic moulds, a subject about which there exists 

 greater confusion in the minds of students than for any other. In the 

 nomenclature, I have followed Gedoelst's " Les Champignons Para- 

 sites." 



In the chapter on media making, it is believed than anyone after 

 reading this section and following the instructions will be able to satis- 

 factorily and without the adjuncts of a large laboratory make any kind 

 of media. The directions as to titrations are given in detail because 

 it is beginning to be recognized that reaction of media in bacteriology is 

 of as great importance as staining is in blood work. 



The section on blood work is practical and gives a method for making 

 a Romanowsky stain which is quick and reliable. The chapter on 

 Normal and Pathological Blood gives in a few pages the more impor- 

 tant points to be borne in mind in considering a possible diagnosis. 



While there is no difference between the laboratory requirements of 

 medical work in the tropics and that in temperate climates, unless by 

 reason of such measures of diagnosis being indispensable in the tropics, 

 it has, however, been my endeavor to treat every tropical question, 

 whether in blood work, bacteriology or animal parasitology, in a more 



