MODERN MICROSCOPY. 



INTEODUCTION. 



THE history of the development of the microscope is exceed- 

 ingly interesting, and itself would fill a small volume : 

 suffice it to say that it was but sixty-eight years ago, or in 

 1824, that Tully made the first achromatic microscope. 

 Since that time, step by step, such progress has been 

 made in its construction as would be scarcely realizable 

 to those w r ho have not followed it. Ten years ago the 

 President of the American Society of Microscopists, in 

 his annual address, remarked ' that lenses which were 

 believed to have so nearly reached the limit of perfection 

 fifteen years ago are antiquated now r , and the theoretical 

 limit of perfection has moved forward like the horizon, and 

 is as far off as ever.' The same statement applies to-day, 

 and even within the last five years lenses have been placed 

 at our disposal by the leading opticians giving results that 

 our microscopical predecessors of fifteen or twenty years 

 ago would never have dreamed of ; and still further experi- 

 ments are going forward, with the view of giving greater 

 advantage in microscopical research. What has been done 

 in the lens part of the microscope has also been effected 

 in the mechanical, and a far better microscope can be 

 purchased to-day for a given sum than a few years ago 

 could be obtained at nearly double the cost, bringing that 



