320 THE ZOOLOGIST. 



large number of instruments are sold which, though well calcu- 

 lated to afford amusement, are utterly valueless for the purpose 

 of scientific investigation. The various parts of a microscope 

 are described seriatim, and that which is useful distinguished 

 from that which is not absolutely necessary to the student. 

 A method of instruction is also indicated : — 



" Next to the improvement effected in the optical construction of the 

 microscope during the last few years, must be placed that of the method 

 of investigation. Formerly almost all microscopic bodies possessing different 

 forms and appearance were considered distinct beings, and were named 

 accordingly. By the present method, prolonged observation is adopted to 

 follow the changes which the individual bodies undergo; whence it has 

 resulted that numbers of them have been found to be simply different 

 stages of each other. Thus a large amount of useless nomenclature and 

 confusion is being removed from the domain of the microscopic world." 

 [Introduction, p. xiii.) 



It was a happy thought on the part of the authors thus 

 instructively to pave the way for a proper use of their work. 



With a view to test the nature of the information conveyed 

 by it, we have turned at random to Acheta, Aphis, Blood, Bone, 

 Cell, Chlorophyll, Crustacea, Desmid, Diatom, Eye, and Fungi, 

 and have been surprised, not only at the amount of information 

 given under these different headings (some of the subjects 

 extending over several pages), but also at the exactness and 

 perspicuity of many of the definitions. 



The labour of preparing such a work must have been very 

 considerable, and if must be gratifying both to authors and 

 publisher to know that they have supplied, in so practical 

 and efficient a form, a want which has been long felt by 

 scientific men. 



It may be well supposed that fifty-three plates (many of 

 them coloured) and more than eight hundred woodcuts (when 

 well executed as these are) add considerably to the utility of 

 such a work. 



