INTRODUCTION. 



STUDENTS who work in properly equipped botanical labora- 

 tories will find therein the needful instruments. Those, 

 however, who use this book at home, as an introduction to 

 the microscopical study of plants, as well as those who, apart 

 from these conditions, wish to become possessed of instru- 

 ments suitable for such work, may perhaps find in the 

 following pages some aid to their choice. 



Starting with the assumption that the instrument is 

 desired for the sake of the work that can be done with it, 

 rather than for its own sake as a beautiful piece of optical 

 and mechanical workmanship, it is well to strongly urge the 

 intending purchaser to buy an instrument constructed upon 

 what is known as the " Continental model ". The micro- 

 scopes built on the so-called "English model" are more 

 massive and complicated in their construction than is realty 

 necessary for student purposes, and the object on the stage is 

 usually moved about by means of a mechanical arrangement 

 of screws, where, for, ordinary purposes, the fingers had 

 better be used. Further, though the diameter of the bod} 7 of 

 the English microscope may oe an advantage, its length is 

 doubtfully so, and renders the erect position of the instru- 

 ment in working, which is for most purposes far the best 

 (though a joint permitting inclination is highly desirable), 

 almost impossible. The distance of the stage from the eye 

 renders delicate working with the fingers a matter of greater 

 difficulty ; for it is notorious that the nearer the fingers are 

 to the eyes, within certain limits, the more delicately their 

 movements can be controlled. Most, or all, of the great 

 English and American makers, such as the well-known firms 

 of Ross, iLtd. ; Powell & Lealand ; R, & J. Beck, Ltd. ; 



