1900] MICROSCOPICAL JOURNAL. 231 



who had faithfully delineated under the microscope the 

 external structure and markings. As in most cases he had 

 made drawings at various periods of the development of 

 the embryo within the egg, this study proves to be one 

 of much interest, as is also the ease with which butter- 

 flies and moths may be classified by the external struc- 

 ture of their eggs. 



Adjustment. — If the microscope requires adjustment, 

 these adjustments should be made with the utmost care. 

 Most microscopes by our best English makers have the 

 wearing parts sprung so that the adjustments may be read- 

 ily effected, but even then a little attention to the tools 

 with which the work is done may be recommended. The 

 screwdriver, for instance, should be in good condition. It 

 is well also to bear in mind that the lacquer on tlie brass- 

 work of the microscope, placed there not so much for ap- 

 pearance as for the prevention of oxidization, is destroy- 

 ed by alcohol. Finally, our advice to the beginner who 

 may wish to oblige a friend by lending him his micro- 

 scope is — don't ! 



Mounting. — The microscope has become quite an art, if 

 not a science, and the list of reagents, stains, and media 

 used for special purposes would be quite a formidable one. 

 Fortunately the requirements of beginners and amateurs, 

 especially those for whom we are now writing, are much 

 more easily dealt with, and we shall confine ourselves to 

 the simplest and most commonly used methods, trusting 

 that as knowledge grows and experience comes with it, the 

 beginner will learn more of such advanced methods from 

 works dealing with the subject. 



It is of course only with very low powers, and when the 

 nature of the investigation admits of it, that an absolute- 

 ly unprepared and unarranged object can be examined. 

 For this purpose a pocket-lens is infinitely preferable to 

 the compound microscope with all its complications and 

 refinements. For examination with the latter instrument 



