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THE SCIENCE OF MICROSCOPY. 



spirit of its teaching should guide the observers hand and eye in 

 all his work, as well as in his estimate of results. And since the 

 microscope is passive and unreasoning in its action, a '^mere tool "' in 

 this sense, the greater fallacy must it be to affirm that its 

 automaton performance needs no initiation, no guidance, no 

 control from the mind of the workman, or that the microscope 

 image interprets itself alike to every e}e, irrespective of differences 

 of natural and acquired powers of vision. Rather may it be 

 asserted that a science of microscopy 7nnst exist before such " a 

 tool '' can be usefully employed since its action is brought to bear 

 upon the most difficult objects under most critical conditions for 

 the exercise of a correct judgment. 



And although the need of special discipline is tacitly admitted 

 in the general effort to acquire what is called a discriminating 

 power, often at that disproportionate cost of time and labour 

 which befalls all self teaching, the art of observing is still 

 incomplete until elevated into a science by supplementing it with 

 precise rules and principles by which its attainment becomes 

 easier, more certain, and more equal in quality. 



For the skill of the microscopist as an observer is distinct from 

 his quahfications as a scientist in his own special line of study. 

 The end and aim of his discipline as a microscopist is to compre- 

 hend aright what he wishes to establish as a scientific fact. And 

 this first grasp of the fact is none the less a result of special 

 discipline because its individual significance (considered in relation 

 to the order of facts to which it belongs) is not here in question. 

 For the general purposes of microscopic science it is important to 

 follow the same rules and methods of procedure in order to obtain 

 under each given condition a just comparison of results. But how 

 much more is certainty and exactitude of facts to be desired when 

 any one of them may become the corner stone of a great generalisa- 

 tion in natural science ! And how little worthy of trust would our 

 generahsations be if we could not assure ourselves of the scientific 

 accuracy of the facts on which they rest. 



