PREFACE. 



THE first and second editions of this work, in 1851 and 

 1853, were intended to furnish a manual on the use of the 

 microscope for physicians and naturalists. The third and 

 present editions aim to be also a compendium of the micro- 

 scopic sciences, but as microscopy reaches its climax in prac- 

 tical medicine this branch of study receives the largest 

 attention. Matters of mere curiosity have been but briefly 

 referred to, while every necessary fact or principle relating to 

 the microscope has been carefully stated and classified. 



By the liberality of the publishers, the chapters on the use 

 of the microscope in Pathology, Diagnosis, and Etiology, 

 which have been added to this edition, have been largely illus- 

 trated with woodcuts from Kindfleisch. 



The Index and Glossary have been combined in this edition 

 so as to be a source of valuable information, and notices of 

 recent additions to the microscope, together with the genera of 

 microscopic plants, have been given in an Appendix. 



No pains have been spared to render this manual a useful 

 companion to the student of Nature, and an aid to the progress 

 of real science. 



July, 1880. 



