vni PREFACE 



it has been our privilege to work. Often, no doubt, they 

 have been somewhat modified or rearranged for the purpose 

 of instruction. We feel, however, that we must give ex- 

 pression to our indebtedness to Dr. E. Klein for many hints 

 and methods which were legitimately acquired by us from 

 his laboratory. Many, if not most, of the useful methods 

 of Bacteriological Analysis current in this country have 

 emanated thence, and we therefore do not hesitate to 

 acknowledge gratefully all the assistance which consciously 

 or unconsciously we have derived from that liberal source. 

 The third part of this little book forms, so to speak, an 

 appendix to the two previous parts, and comprises an intro- 

 duction to Bacteriological Chemistry for those who are 

 desirous of devoting some of their time to advanced in- 

 vestigation and research work. Bacteriological Chemistry 

 is yet a young and unfledged science, even more unsatis- 

 factory than Physiological Chemistry. We have therefore 

 selected a few points in the shape of exercises which are 

 either of classical importance or essential for research. 



A. A. K. 

 J. H. D. 



LONDON, Zlst December 1894. 



