98 SELECTION AND I SE 



may require, a word of caution is also necessary. If your 

 studies require the employment of the very best instrumental 

 appliances, by all means procure either a first-class stand by 

 some well-known maker, or a microscope made to suit your 

 special requirements. But at the same time do not fail to pro- 

 vide yourself with one of what may be called the third-class in- 

 struments ; that is, a microscope of moderate size, and destitute 

 of those complicated arrangements which are the glory of all 

 first-class stands. With such a microscope you will be able to 

 do twice, yes thrice as much work as with the large heavy 

 stands. The physician or working naturalist that procures a 

 very expensive stand for every-day use, makes a great mistake. 

 It is very well to have such a stand for special occasions, but 

 for " ordinary work " the small stand is to be preferred. 



And this leads us to enquire what is or ought to be meant by 

 "ordinary work ?" The expression is not an uncommon one, 

 but it is one to which objection has been made on account of 

 alleged indefiniteness. 



If we exclude from consideration the employment of the micro- 

 scope for purposes of amusement or of elementary instruction, 

 almost all microscopic work may be divided into two classes, 

 which may very properly be called, respectively, ordinary work 

 and purposes of research. Ordinary work in this sense consists 

 chiefly in searching for known forms, and does not demand 

 anything like the instrumental perfection which is required for 

 work which at all approaches the nature of original research. 

 And by original research, we do not mean that research which 

 is carried on for the purpose of making important scientific dis- 

 coveries, but simply that which has for its end the examination 

 of the structure and characteristics of objects which are un- 

 known to the individual observer. 



In support of this view, it would be easy to cite numerous 

 instances. Thus every one knows, that for the examination of 

 different kinds of starch, and the investigation of their peculiar- 

 ities, very good microscopes and high powers ought to be used. 

 But Hassal, in his work on adulteration, tells us that a quarter- 

 inch objective, of ordinary quality, and used on a common 

 stand, is sufficient to discriminate between the different starches 

 they are mixed together, 



