VI INTRODUCTION. 



affairs. No such elementary but comprehensive work 

 exists in Enghsh among the numerous able treatises upon 

 special branches of the subject. The present volume is 

 therefore the outgrowth of a pedagogic need. The book 

 is necessarily incomplete from the standpoint of the 

 expert in any of the branches which it treats, but if it 

 conveys to the student's mind such an idea of the possible 

 applications of the microscope in varied fields as shall 

 stimulate him eventually to the further exploration of 

 some one of them, it will have served its purpose. 



In the preparation of this volume, the authorities 

 quoted in connection with the various chapters have been 

 freely drawn upon. The author further desires to ex- 

 press his grateful obligation, to Dr. P. G. Stiles for the 

 preparation of original drawings; and for advice and 

 assistance in regard to various portions of the manuscript 

 to Professor W. T. Sedgwick, Professor Mary A. Willcox," 

 Professor H. M. Goodwin, Professor F. J. Moore, Pro- 

 fessor C. H. Warren, Dr. C. C. Simmons, Mr. A. E. 

 Leach, Mr. A. G. Woodman, Dr. E. L. Walker, and 

 Miss A. F. Rogers. 



Acknowledgments are due to the authors and pub- 

 lishers of the following books for figures which have 

 either been copied directly or redrawn : 



Deschanel, a. p., and Everett, J. D. Elementary Treatise 



on Natural Philosophy. New York, Appleton & Co., 1894. 

 Hager, H., and Mez, C. Das Mikroskop und seine Anwendung-. 



Berlin, J. Springer, 1899. 

 Carpenter, W. B., and Dallinger, W. H. The Microscope 



and its Revelations. London, J. & A. Churchill, 1891. 

 Gage, S. H. The Microscope. Ithaca., Comstock Publishing 



Co., 1904. 



