186 



greater than purchasing a new objective of the 

 same power and it would not even then be equal 

 to the latter. 



Accessories. We have already stated in the 

 body of this book which accessories are considered 

 useful. Some of them are absolutely necessary in 

 some special lines of work, in which case however, 

 the student is generally conversant with the re- 

 quirements and may make a suitable selection, 

 but for all general purposes some accessories are 

 necessities where others are only conveniences 

 and we append a list of such which, unless pro- 

 hibited by necessity, should accompany each outfit. 



Abbe substage condenser, preferably the com- 

 plete substage attachment giving all adjustments. 



Double, triple or quadruple nosepieces according 

 to the number of objectives accompanying the 

 microscope. 



Abbe camera lucida. 



Revolving or attachable mechanical stage. 



Eyepiece and stage micrometer. 



Mounted objects, Proboscis of Blow-fly and P. 

 angulatiiui, dry. 



Pocket magnifier, preferably Aplanatic or Hast- 

 ings triplet. 



Cover glass gauge. 



Flat-wick oil lamp. 



Dissecting stand or dissecting microscope. 



