PREFACE. 



THE progress of microscopic science may be well illus- 

 trated by a comparison between the present and former 

 editions of this book. The author's intention was to 

 place within the reach of the student of nature a com- 

 pendium of microscopy, free from unnecessary verbiage, 

 which should aid in every department of natural science. 

 It is 110 small compliment to such a work that for a 

 quarter of a century it should hold a place among works 

 of reference, although surrounded by larger and more 

 pretentious volumes. In order to meet the request of 

 the publishers for another edition, it has been found 

 necessary to rewrite the entire book, and although the 

 original design has been kept in view, the numerous 

 additions to our science render considerable enlargement 

 needful, notwithstanding the effort made to concentrate 

 the material into the smallest compass consistent with 

 perspicuity. 



The vision of microscopy sweeps over all the world, 

 and embraces all forms of organic and inorganic ex- 



