THE MICROSCOPE 

 AND MICROSCOPICAL METHODS 



INTRODUCTION 



IN dealing with the possibilities and use of any method of investi- 

 gation, any machine or piece of scientific apparatus, the writer or 

 teacher will naturally proceed as seems to him best from his personal 

 experience, from his general theory of education, and from his con- 

 ception of the style and method of presentation which will render 

 his book most acceptable to his possible readers. 



As stated in the preface to the sixth edition, this book had its origin 

 in the laboratory, and its purpose was, and still is, to give the guidance 

 by which those unfamiliar with the microscope and the methods of 

 work with it can gain an intelligent understanding of the instrument, 

 its limitations, and its possibilities for aiding one to arrive at truth. 



In working out the plan the following landmarks have been kept 

 constantly in sight: 



(i) To most minds, and certainly to those having any grade of 

 originality, there is a great satisfaction in understanding principles; 

 and it is only when the principles are firmly grasped that there is 

 complete mastery of instruments, and full certainty and facility in 

 using them. The same is true of the methods of preparing objects 

 for microscopic study, and the interpretation of their appearances 

 when seen under the microscope. 



Much good work can be and has been done by the rule of thumb 

 method, in which there is no real understanding of the underlying 

 reason for any of the operations; the worker simply knows that good 

 results follow a certain course of action. Probably most of the work 

 of the world is done by rule of thumb. But the originators of the 

 knowledge making rule of thumb possible must have some compre- 



