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PREFACE, 



BY PROFESSOR STRICKER. 



THE Science of Histology rests on more numerous and more 

 exact observations than any other department of knowledge. 

 The microscope effects the enlargement of the image falling 

 upon the retina, and by thus diminishing the extent of surface 

 that can be examined at once, we gain proportionately in 

 sharpness. 



Constant practice enables us to raise the acuteness of our 

 perception of luminous rays to an extraordinary degree. We 

 place ourselves in a convenient position ; we put away from 

 us all extraneous disturbing impressions on our senses, and 

 even concentrate the sensation of light upon one eye. Nay, 

 more, we even endeavour to save this organ every secondary 

 or subsidiary effort, neither permitting it to roll nor allowing 

 any accommodation to be effected. We take, SQ to speak, the 

 eyeball into our very hands, we accommodate it by a screw, 

 and turn it about by means of a mechanical stage. 



Our region of observation, thanks to the improvements 

 in the microscope, has not only waxed in breadth during the 

 last ten years, it has also gained in depth and clearness 

 through the distribution of the " lights " of careful obser- 

 vation. In yet another direction, too, is our sphere bein^- 

 enlarged. Histology is constantly and steadily advancing to 

 the dignity of a comparative Science. Each worker conse- 



