INTRODUCTION. 



GENERAL METHODS OF INVESTIGATION. 

 BY S. STRICKEB. 



THE microscope is a means of research. When objects are so 

 small that at ordinary distances from the eye they no longer 

 produce sufficiently large images on the retina, they require, 

 for their examination, either a simple or a compound micro- 

 scope. The domain of investigation embraced by this instru- 

 ment, however, does not limit research. Microscopy defines no 

 doctrine, but is simply a method of examination : yet it is the 

 most delicate with which we are acquainted for terrestrial 

 objects, because modern microscopes are the most perfect of all 

 optical instruments. 



Up to the present time the microscope has been chiefly ap- 

 plied to the investigation of the various organisms ; and our 

 knowledge of the finer structure of plants and animals, and 

 especially of the latter, has assumed the character of an inde- 

 pendent science, which again presents important subdivisions. 

 The observation of healthy tissues, and of those modified by, 

 or originating in, disease, already constitutes the basis of two 

 separate but closely allied departments of science, each of which 

 can again be regarded from different points of view. We can 

 for example, push our inquiry either into the morphology or 

 into the biology of the tissues; or, as it may be otherwise 

 expressed, into the normal or pathological anatomy and phy- 

 siology of the tissues. At present, however, the morphology and 

 physiology of the tissues are so intimately connected with each 

 other that no line of demarcation can be drawn between 

 them. The observation of the vital phenomena presented by 



