XX INTRODUCTION. 



Bausch & Lomb, and Zentmayer have recognised the need 

 for instruments of more compact form, simpler construction, 

 and lower price, and, under one name or another, have 

 brought out instruments on the lines (many of their faults 

 included) of great Continental makers, such as Zeiss, Leitz, 

 Seibert, Eeichert, Hartnack, etc., whose microscopes are to 

 be found by the thousand in the great laboratories of the 

 European Universities. 



Putting upon one side, then, alike the more elaborate and 

 expensive instruments of microscope manufacturers, and 

 those in which everything is sacrificed to cheapness, micro- 

 scopes suited for student use may be roughly placed in two 

 groups; the one containing comparatively simple instruments, 

 a reasonably good microscope reduced, so to speak, to its 

 simplest terms, in which the apparatus consists only of a 

 means for steadily supporting and illuminating an object to 

 be examined, and magnifying it with accuracy to a moderate 

 extent ; and the other group comprising instruments of a 

 higher quality, to which accessory apparatus for illuminating 

 or examining are, or can be, attached, and the magnifying 

 capacity of which is of a higher degree of excellence. The 

 first of these groups contains instruments which are quite 

 suited to the greater part of the microscopical work detailed in 

 this book. But should the student have ambitions, and not 

 merely wish' to study those few parts of this book which are 

 comparatively inaccessible with the simpler instruments, but 

 be desirous of providing him or herself with a microscope which 

 may hereafter be used as a means to wider study, or even, may 

 be, for the broadening of knowledge by new investigations, 

 then a microscope selected from the second category becomes 

 a necessity. It does not follow that the whole of the ulti- 

 mate expense must be incurred at once, but it rs essential 

 that the microscope stand which is purchased shall be of a 

 kind to which subsidiary apparatus can be fitted, and which 

 will provide a suitable support for higher magnifying powers 

 than those which may in the first instance be purchased. 



The microscopes provided for early student use in botanical 

 laboratories belong to the former of these groups, and will 

 probably be found to have a magnifying capacity up to 400 



